The phrase "flapping at the window" shows up a lot in Bram Stoker's Dracula. Unfortunately, my filthy, filthy mind likes to erase the letter L...
"I was waked by the flapping at the widow", then, results in a fit of giggles that lasts for several minutes.
Also, I just realized that "fap" and "fapping" are onomatopoeia. Feel free to throw that one out there the next time your English teacher asks for examples, high school students!
Other moments in the text that my brain likes to construe as somehow dirty include:
"You go wake those maids. Flick them in the face with a wet towel, and flick them hard."
"I shall be patient, Master. It is coming--coming--coming!"
I should really keep a running list.
Of course it doesn't help that, during my King Arthur and Robin Hood class, we dwelled on the fact that the Middle English pronunciation of "shoot", as in "to shoot a penny", sounds a lot like "shit". The line "I wil not shete a peny" inspired much mirth this day. Sometimes I swear Middle English literature is nothing but one huge, prolonged fart joke.