Your Forehead!
Well first you have to pull really really hard.
Someone who isn't that smart or isn't nice. Synonyms: stupid; idiot; mean; cruel; jerk
It appears that beavis who is 17 is about 5'2 or 5'3 and butthead who's also 17 is 5'5 to 5'7, but in the beavis and butthead do America movie they are only 3'10