The New England region of the U.S. just got hit with a massive (30-inch) snowstorm. A friend of mine from Massachusetts wrote on Facebook:
Onto our third basket of firewood since noon. I think this is evidence that crap wood is crappier than non-crap wood. Before I ordered the crap wood I read that this was the case, and lo, it is true.
My friend is British, so her repeated use of crap as an adjective did not surprise me. But her use of crappier was interesting. Certainly, crappier is the appropriate comparative for the traditional American adjective crappy. (“The show … was on the crappy side,” The Catcher in the Rye.) But not for crap, I wouldn’t think.
However, no alternative presents itself. Certainly not crapper–a Google search for that word yields only results related to Thomas Crapper. More crap doesn’t sound right, either. So I put it to NOOB readers: what word do you use to indicate something that surpasses some other thing in the degree to which it is crap?
notoneoffbritishisms.com 
I am British and would say “X was even more crap than Y”, but that’s just me!
Perhaps it is because in BrE “it’s crap” is already a superlative, or at least a complete and final negative verdict. “It’s crappy”, on the other hand, means just relatively bad and can therefore be made stronger.
It’s quite regular: crap, crappier, crappiest
Wot Bill sez.
“X is in the crapper.” X is obeying a call of nature.
“It’s down the crapper.” All hope for whatever “it” is has been extinguished.
Wouldn’t want to split the vote, but I’d use crappier, even more crap than, and even crappier still.
And does it all stem from the man who gave us the W.C.?
Thomas Crapper did not invent the WC. The first popular public flushing loos in use in the UK were at the Great Exhibition of 1851 at the Crystal Palace in Hyde Park, but they were invented some years before. In 1851 Thomas Crapper was only 14 years old and working as an apprentice plumber in Chelsea. Crapper did become one of the major manufacturers and suppliers of flush toilets in Britain, but his name is entirely coincidental.
More details http://www.exnet.com/1995/11/01/science/science.html and http://en.wikipedia.org/wiki/Thomas_Crapper#Origin_of_the_word_.22crap.22
It seems to me this is not a question of how one should refer to an item which has surpassed another in its lack of quality. On this, surely we all agree. The word is ‘crappier.’
Rather, the problem seems to arise when one uses ‘crap’ without adding the ‘y.’ Do the Brits among us use shitty, shittier, and shittiest? Or do you refuse the ‘y’ in adjective form there as well?
I believe most Americans happily refer to some items as ‘crap’ or ‘shit’ without adding a ‘y,’ but only if renaming the object (noun form). We do not use these forms as adjectives.
Eg) “This computer is crap.” VS “This crappy computer…”
Also perfectly acceptable is, “This computer is crappy.”
Also, where I grew up (southern US) a ‘crapper’ is either a toilet or the room in which it is located. I’m surprised this didn’t come up in your google search.
See http://www.urbandictionary.com for definitions of crap, crappy and crappier.
The definition of crappier includes “California is a crappier version of Florida”. Never having been to either I cannot comment, but it is clearly in use in the USA.
Crappier is correct as is shittier, and shittiest. However, ‘absolute shite’ should cover the whole kit and caboodle…
James Brett: It did. In the google search which brings up Thomas Crapper.
Thanks, Adrienne, for clearing that up. And NOOB, for teaching me who Thomas Crapper was and from where this name for a toilet came.
James – read the comments above, and learn that Mr Crapper did NOT give his name to the crapper.
Possibly because crapper and shitter are already recognised nouns in British English. Crapper, as mentioned above, is the toilet; shitter is either the same, or the back passage, which gives rise to the delightfully macabre rhyming slang of the ‘Gary Glitter’, as in ‘right up the Gary Glitter’. I’m not sure if our cousins across the pond are aware of the downfall of 70’s glam-rock star GG, but the slang is apt.
Crappier and shittier all the way (from the UK).
crap is just the shortened form of the adjective. crap is a noun to which ‘y’ is added to make an adjective, cream > creamy, so it follows the usual rules for adjectives ending in -y in terms of the comparative and superlative.
In Aus, exactly as Bill said: crap, crappier, crappiest. Methinks that “crappy” is used more often than plain “crap”: “What a crappy film”, “That was crappy” would more common than “What a crap film”, “That was crap” (cf JamesBrett). Perhaps someone could enlighten me on the grammatical distinctions here.
My feeling is also that in this country “crap” is much less associated with excrement than in the US or UK. I’ve never heard “crapper” used for “toilet”. It’s primary sense is “bad”, and I suspect many people wouldn’t associate it with excrement at all until they were subjected to a re-run of that worst-in-series “Carry on Round the Bend/At Your Convenience”.
Crapper for toilet is common in Canada as is crap used as an adjective. For example: We have a crap government right now; their policies are total crap and belong in the crapper.
Where does crapfest come from?
It’s almost certainly a fairly recent Americanism.
The OED also lists:
slugfest, lovefest, gabfest, crapfest, talkfest, gorefest, snoozefest, hatefest, bitchfest, snorefest, geekfest, gabfest, bloodfest, blogfest, songfest, shitfest, screamfest, filmfest, yawnfest, funfest, sobfest, plugfest, mudfest, fragfest, and suckfest.
hmm, we (BrE) defenitely use both shit/shitty shittest/shittiest.
Shitter tends to be a noun as mentioned above.
I’m guess the terms are largely interchangeable but I do have a sense that shit/shittest tends to be more concrete “That’s the shittest x I’ve ever seen” and shitty more abstract “she treated him shittily” though I could be talking shit I suppose.
Crappy is rare in my experience though the most crap is definitely crappiest.
In England a crapper is a not that heavily used but generally well-recognised term for a toilet or lavatory (at least in the south and for the working/middle class ‘the loo’ is the most common colloquailism for the toilet and the room its in – we almost never say bathroom when we are asking where the toilet is)
Here you might well say something has just got crapper but it would be much more common to say crappier.
But one can be pretty flexible tense-wise about whether you use crap or crappy.
I’m British, and I’m sure I’ve used the term “significantly crapper than…,” but it doesn’t sound right without the adverb in front for some reason…
It’s not clear whether “crap” in these contexts is (1) an adjective zero-derived from the noun “crap” or (2) simply the noun itself being used (attributively or predicatively) to qualify another noun. In the latter case, there would be aversion to inflecting “crap, crapper, crappest” in the same way as there is (in all dialects) continuing resistance to “fun, funner, funnest”.
There is in fact a single relevant match in the British National Corpus: “I don’t know why (unclear) (SP:PS4YX) really crap. Really is and (unclear) even crapper.”
To avoid false positives, you could also search for “crappest” (though you’ll get some thous, forsooth) or “even crapper”.
Personally, it’s always shit, shitter, and shittest; and crap, crapper, crappest. I would only use shitty in the context of a “shitty nappy”. I’ve never said crappy before in my life.