she wanted to find some shaggy dog jokes, so she looked them up in the index. didn't see any. she flipped through the book. didn't see any. for all i know, she read the whole thing front to back (i hope not - after awhile, reading a long list of short jokes gets to be like reading a dictionary). now, i have to admit that, when i had looked at it, i had checked the index and flipped through also, looking for shaggy dog jokes, because i love them[1]. i couldn't find any either, and i didn't realize until she was telling me today about how she went through the whole book and didn't find a single one that the whole book WAS the shaggy dog joke, and we both got zinged. i started laughing, and couldn't stop for maybe five minutes, while my mom is just getting more confused.
you see, she had no idea what shaggy dog jokes are. she thought they would all be about shaggy dogs.
[1] a lot of my favorite jokes can be described as such: someone tells it to you, and you are either annoyed at the stupidity adn waste of your time, or horrified at its tastelessness, and you think the person who told you is a big jerky slimeball for subjecting you to it. then a few hours later you go out and tell it to all of your friends. wash, rinse, repeat.