What Makes Up the Name: shit + fart
Speaking of crap, this one is usually only something you have to worry about if you're very old or very young (or a little old and very hungover). When you try to push one out just a little too hard, this will happen. Like that time on your roommate's chair.
Origin: We think the coolest grandpa in the world came up with this term in the 1870s, but we can't verify that. It also appeared in the 2004 script for Along Came Polly and has since entered the vernacular.