A form of pill popular in early 90s rave culture, where extacy was supplied in red and black capsules, named after the 'Beano' comic strip character. see also Rhubarb and Custard
"Hey man, what you got"
"I got some Dennis the Menace... Have you been menaced yet!?
These things will have you dancing on the stage with your trowsers round your ankles."
A sexual situation in which a man removes a condom after thorough use(filled with semen), places the filled condom in a slingshot and launches the payload at an unsuspecting female companions face. The condom hits the woman with a humiliating, stinging and resounding slap. The male then shouts: "Dennis the Menace, bitch!"
"Did you hear that Scott "dennis the menace'd" his girlfriend last night!?"
"No way! I bet she was pissed!"
"I don't know, I think he was too busy playing WoW to notice."
this is used as a slang term for anal, or "butt sex"
I could tell when Justin and Eli exited their bedroom they were up to some dennis the menace by the smell that filled the room.