The substance that accumulates in the crevice between the buttocks. Typically composed of sweat, dead skin cells, environmental soil, and trace amounts of feces, its production is often facilitated by rigorous activity or long intervals without bathing. Known to possess a rather unpleasant odor and foul taste.
I say, how old is this yogurt, mother? It tastes like ass butter.
Assbutter is an english translation of the word rövsmör and is made by depositing your "man milk" into someone's ass and churning it with your rod. It's mostly used to be as disgusting as possible.
It originated from Northern Sweden.