Jeff Foxworthy, famed for the You Might Be A Redneck If... jokes, has one go "If you've ever had to carry a bucket of paint to the top of a water tower to defend your sister's honor, you might be a redneck." Awfully specific requirement in the test. According to the music video, it's "Dee Dee is a who"; he's already painted over the rest.
A lot of those jokes could vaguely be considered Noodle Incidents ("If you've been blacklisted by a bowling alley," "If you were ever too drunk to fish," etc.). Subverted on the Blue Collar Comedy Tour by Bill Engvall with "If you've ever popped a beer during a eulogy," after which he went on to explain about his uncle...
Lewis Black's famous "If it wasn't for my horse, I wouldn't have spent that year in college" bit is based on him overhearing said remark. He advises the audience not to think about it too much, lest their heads explode.
Steve Martin: "I was sitting at home, doing horrible things to my dog with a fork..."
Sean Lock, as the introduction to a series of jokes about shame: "You'll be walking down the street, and suddenly you stop dead in your tracks. Your friend asks, 'what're you doing?' 'I suddenly remembered that time in the hotel room with the badgers.'"
In one of Mike Harding's monologues about growing up in Crumpsall, he recollects his father slapping him round the head and saying "you never did own up to where you got that Davy Crockett hat, did you, you little bugger?" This is followed by a mysterious reference to a neighbour's missing cat, but is never followed through.