What you say when somebody is being really annoying or stupid. You usually look at them for a second, shake your head from side to side with your mouth slightly agape, and let it go. "EHHUH". (Great to make yourself feel better in arguments.)
Liam: "I wish you would just shut up!"
Gary: "EHHUH"
When a person is acting incest or has incestuous tendencies.
Cleetus: "Bro my cousin was looking kinda hot at that party"
James: "Hey you are acting pretty Alabamic right now."