Verb, transitive, from the brand of vacuum cleaner, which was apparently hugely popular in the U.K in the mid-20th-century period. The OED reports that the literal verb–that is, to clean by means of a vacum cleaner–appeared no later than 1939 (impressive, since Hoover was patented only in 1927). The first cite for the metaphorical verb (“To consume voraciously; to devour completely. Freq. with up or (occas.) in”) is from the 1970 Times: “The populace‥sit hoovering up the drivel poured out on television at peak viewing times.” A Google Ngram suggests that, as with so many Britishisms, U.S. use started to rise in the early 90s and is still going up.
Urban Dictionary offers two additional meanings for the verb. One of them you can guess. The other:
Being manipulated back into a relationship against your will with threats of suicide or self-harm, threats of harm to others or property, or threats of false criminal accusations. A “hoover” is relationship blackmail. This slang term is often associated with individuals suffering from personality disorders like Borderline Personality Disorder or Narcissistic Personality Disorder.
“Where are we rolling?” “Into the heart of the night. Wherever there are dances to be danced, drugs to be hoovered.” (Jay McInerney, Bright Lights, Big City, 1984)/For years, Mr. Madoff’s elusive genius act beguiled his Jewish neighbors, as well as friends of those neighbors, and so on, and so on, until vast chunks of local money were hoovered into his Ponzi scheme. (New York Times, April 11, 2009)