Since 1999, when UrbanDictionary.com was founded, the web-based tome has become Internet de rigueur for cybernerds in need of a crash course on the latest cultural slang. At the end of 2012, the site was nearing a staggering 7 million definitions. And regardless of what you think of the online wordbook, it's an impressive feat to behold. So in the spirit of scholarly research, we've collected the 40 funniest definitions on UrbanDictionary.com. This is proof that learning can be fun.