The act of a man having sex with a woman by repeatedly stroking his penis under her armpit. The term is similar to armpit sex, the armpit fuck, or dick in a headlock. However, it differentiates itself through the use of household items such as butter, margarine or cream as a lubricant to entice the woman to lick the penis as it protrudes from her armpit.
Man, I got a mean burn in my armpit from a Molly McButter last night.
I had to de-grease my penis after giving some Molly McButter to my old lady.
an enormously obese transvestite that has duckbutter seeping from the anal cavity of the rectal sphere, while staining the pants and can only be removed with Tide.