Both the man and the woman start out naked. The woman allows the man to put ~1 pint of whipping cream into her anus. The man then wraps a doritos bag around his penis and uses it as a condom.
The man then proceeds to fuck the woman anally while wearing the doritos bag condom as protection. This continues until the whipping cream has been churned into butter.
The butter can then be put on toast or used in another sexual act.
They used the rest of the butter on their toast.