I find auto correcting humor particularly hilarious just because it is something that happens to me all the friggin' time. Apparently on various types of smart phones you can change the auto correcting functions to change words into other things you would prefer. I wouldn't know anything about that as I have a Sadberry - I mean Blackberry. So a great way to prank friends is to change these settings on their phones while they are distracted. Like changing now into meow. Hilarity will ensue.
Check out a whole page worth here. Warning NSFW - Very Strong Language.
-Via Hyper Vocal