(slang) A line in a film etc that elicits such a laugh.
[Churchy, directing a comedy:] All right, Albert, here's your boff gag... You say, "What's that in the road a-head?"
[Albert, actually seeing one:] A head! A head in the road!
[Churchy... eventually seeing it:] Stop clownin'... This sure-fire joke is serious—you got the line all... wrong? 1959 July 19, Walt Kelly, Pogo, Sunday, comic strip, →ISBN, page 243:
(slang) To have sexual intercourse with (someone).
Deke and LaVerne could go out to Cascade Lake together and plow the back forty all night; he would not be delighted with the knowledge that they were boffing each other's brains out, yet neither would he be surprised. 1982, Stephen King, The Raft:
I am paying no attention to them, because they are drinking local ale, and talking loud, and long ago I learn that when a Boston character is engaged in aleing himself up, it is a good idea to let him alone, because the best you can get out of him is maybe a boff on the beezer. 1937, Damon Runyon, A Piece of Pie:
[…] something he'd found out the hard way when he was dating Kimberly Haney back in high school and her brother, Chad, big linebacker on the Roosevelt Roughriders football team, had taken exception and boffed him upside the head. 2014, Waverly Curtis, The Chihuahua Always Sniffs Twice, page 135: