Neither Here Nor There, whenever Bryson's 1973 backpacking tour of Europe with Katz is mentioned. The best bit is probably at the Louvre: "There's nothing but pictures and shit in this place!", and the painting of the two aristocratic ladies with one's finger 'plugged casually into the other's fundament' ... 'this was an activity quite unknown in Iowa'.
From the same book, the extended digression -- while in the Hamburg red-light district -- on the practicality of blow-up dolls:
"I couldn't handle the tension. Imagine having friends drop in unexpectedly when you were just about to pop the champagne cork and settle down for a romantic evening with your vinyl companion and having to stuff her up the chimney and then worry for the rest of the evening that you've left the box on the bed or some other give-away lying around. ('By the way, who's the other place-setting for, Bill?')"
The Hostess cake incident in A Walk in the Woods (also involving Katz), especially the outcome.
Katz's revenge on the drunken "hikers" who drive them from a shelter; '"You know that woman who said 'ewww do we have to share?... I did something kinda bad". He opened his hand and there were two suede shoelaces.'
Frankly, whenever Bryson writes anything, the chance of this trope occurring approaches one exponentially with every sentence.
Then there's the story in "A Short History of Nearly Everything" about the severed head that rolls into someone's house.
As always most of his book The Life and Times of the Thunderbolt Kid counts. Especially the scene where his friend's father jumps off a high diving board.
In At Home, Bryson mentions an old cautionary poem about a little girl who plays with matches and sets herself on fire. He describes the accompanying illustration as "showing a young girl engulfed in a ball of flame, on her face a look of profoundest consternation".