sports
Explanation
The Joke
A couple is in bed together, and the man is desperately trying to delay his sexual climax. He frantically thinks: "Oh God, not yet, you have to last longer than 30 seconds. Think about... boxing!" But this backfires: "Crap crap crap, Chris is so hot. Think of something more boring! Baseball! Baseball!" That does not work either: "It's not working! More boring! Soccer! Soccer!" He keeps escalating to increasingly less exciting sports: "Dammit! Golf! Oh no, golf!" then "Curling, croquet, NASCAR, AAAH! Nooo!" Finally he lands on: "Senior league bowling. Senior league bowling!" -- apparently the least arousing sport he can think of.
The Humor
The comic plays on the well-known trope of men thinking about unsexy things (traditionally baseball or math) to avoid premature ejaculation. The twist here is that every sport the man tries to think about somehow fails to be boring enough, forcing him to descend through a hierarchy of sports ranked by their perceived boringness. The comedy escalates as he burns through baseball, soccer, golf, curling, croquet, and even NASCAR -- each one apparently still too exciting. The final answer, "senior league bowling," is the ultimate anti-arousal image. The comic also subtly pokes fun at sports fandom by creating an implicit ranking of sports from most to least exciting, with the progression itself being the joke.