In 1979-80 I took an (analog) electronic music class at New England Conservatory with Robert Ceely (other students in it included Alvaro Cordero, Tom Laskey, and Richard Danielpour) in which one of the assignments was to learn how to say things backwards -- by saying them, recording them, running the tape backwards, parroting the backwards version, recording it, and playing THAT backwards. The new versions sound pretty stilted, and hilarious. And as it turns out, that's how they made the dwarf in Twin Peaks sound so funny when he talked.
About five years ago I got a Yak Bak in the shape of a pen (the ink ran out long ago) that plays back what you say into it forwards or backwards. It was five bucks, closeout, at Toys 'R' Us. I have learned several things backwards in order to use the pen as a party trick at parties where things have slowed to a lull, or simply to call attention to myself. Here are some of the things I can say backwards, recorded straight from the Yak Bak pen. Run your mouse over the first set of words (this seems not to work on a Mac) or click on the second set of words.