Green’s Dictionary of Slang

(US) to insert drugs or alcohol into the anus so as to intensify and speed up the experience.

1983		B. M. Kavanagh High School Yr Bk 🌐 Judge — Have You Boofed yet?
2004		Urban Dict. 20 Sept. 🌐 boofing. the act of consuming alcohol via the anus, for rapid buzz.
2009		Urban Dict. 5 May 🌐 boofing. The act of inserting drugs into the anus for a longer trip. Most often occurs at Disco Biscuits shows by spun-out kids on ketamine.
2023		Rayman & Blau Riker’s 169: [A]nytime you’re out of your cell, the contraband is boofed. You keep it inside you [...] 174: We found the gun. Twenty-five automatic. Something they could boof up their ass.