Assfoot is what happens when Dad finds you masturbating while peeping through a hole in the downstairs shower, to your mom, sister, cousins, etc., anyone with ass, cunt, and tits.
Assfoot is when Dad sticks his foot up your ass for peeping tomism.
Derived from the Soul Caliber character "Astaroth" an asstooth is a big, bumbling, klutzy galoomph of a person who is obviously doing something that requires negative use of the brain.
"No, it's probably NOT a good idea to stick your hand in the waffle iron, asstooth"
"whatever ,asstooth" - usually said in exasperation when someone keeps talking about the new plumbing they're installing in their bathroom.