A polygamous sex act in which a women lies on her shoulders with her legs up in the air spread at about 90 degrees. One man stands perpendicular to her and between her legs, and positions his penis straight down into her vagina. Two other men (or women if they have the upper body strength) stand on either side and hold on to the woman's ankles. They then pull her up and down onto the man's penis, using her legs just like the handle on a butter churn.
Dan, Mike, Cindy, and I were bored last night after Scrabble-O-Rama so we turned that bitch into the butter churn.
When you pour warm milk in a girls vagina and alternate fucking speeds until it solidifies into butter...the next morning you trick her into eating said butter.
Guy: We Made good butter last night while we did the Butter Churn.
Girl: Yea...mmm this toast is good.