Well, I was just rereading a book I helped write around May last year,
Deadly Games, by E.N.Publishing. I'd forgotten some of the stuff I'd put in there. Actually, I was just the editor, and it was a monster of a project to keep all sorts of monster stats and locations clear in my head. I apparently found a means to relax by putting in a few really inane jokes.
The maps of the dungeons are labeled, and each room or location is an 'area.' For example, Area 13 contains 2 large spiders, etc. Well, do a search for the text 'Area 51' if you own the book, and maybe you'll think I was funny.
Later, there's one dungeon with a few rooms labeled by letter rather than number. They go all the way from A to O and beyond, and certain triggers can seal these room so monsters can't get out. Trigger 1 seals B and C, trigger 2 seals F and G, etc. Well, trigger 3 seals L, M, N, and O. You wanna know why? In the Adam Sandler skit 'Respect,' little Nicky Dechezeray sings his ABCs, sort of hesitantly, and all his older relatives are commenting on his performance. When he gets to the part, "H I J K LMNO P," one guy comments, "LMNO, they always go together."
Some of the jokes are things only I'd get, like Pepe Luapa, a halfling sorcerer character, who is named after the only French character I've ever allowed in one of my D&D games. He was a thousand walking stereotypes, and the statblock in the book even includes an entry for cigarettes. You might not find them funny, but 8 months in hindsight, God I'm glad I worked on this book.