A backwoods, hillbilly, redneck, less than educated or possibly humorous way of saying "or else".
1. "We need some gas Cletus, elsen we ain't gonna make it to town!"
2. "Keep yer hands off my sheep Rosco, elsen Ima kick yr ass!"
3. "Don't cough your head off Teri, elsen you're going to dance crooked!"
something you say hi to.