I googled one metaphor I remembered being funny, just to get it right. Found it, and these others:
Her face was a perfect oval, like a circle that had its two sides gently compressed by a Thigh Master.
His thoughts tumbled in his head, making and breaking alliances like underpants in a dryer without Cling Free.
He spoke with the wisdom that can only come from experience, like a guy who went blind because he looked at a solar eclipse without one of those boxes with a pinhole in it and now goes around the country speaking at high schools about the dangers of looking at a solar eclipse without one of those boxes with a pinhole in it.
She had a deep, throaty, genuine laugh, like that sound a dog makes just before it throws up .
Her vocabulary was as bad as, like, whatever.
He was as tall as a six-foot-three-inch tree.
The little boat gently drifted across the pond exactly the way a bowling ball wouldn't.
Her hair glistened in the rain like a nose hair after a sneeze.
The hailstones leaped from the pavement, just like maggots when you fry them in hot grease.
The plan was simple, like my brother-in-law Phil. But unlike Phil, this plan just might work.
The young fighter had a hungry look, the kind you get from not eating for a while.
He was as lame as a duck. Not the metaphorical lame duck, either, but a real duck that was actually lame, maybe from stepping on a land mine or something.
The ballerina rose gracefully en pointe and extended one slender leg behind her, like a dog at a fire hydrant.
It was an American tradition, like fathers chasing kids around with power tools.
She walked into my office like a centipede with 98 missing legs.
It hurt the way your tongue hurts after you accidentally staple it to the wall.
Evidently, some or all of these are quotes from High School essays.