Your getting something unexpected stumbleupon style, but you are controlling the seed of randomness, making it more interactive and game like.
The funnest thing is entering random letters\nonwords. For example "rowlz".
Glitch with "exact search"? It used to return different results last night like best match, but now seems to be literally searching "undefined"
edit: whatever the change was, this guy is going to get a lot more hits now and the site isn't quite as funny: http://www.youtube.com/watch?v=tNR6aEdwRNI
edit2: nvm it appears to be fixed now.