When one party member offers to give fellatio to another party member (joke or not), the former party member is obliged by the Fellatio Code to follow up on the aforementioned action of fellating the latter party member.
If the offering party member hereupon refuses to perform the offered fellatio, she (or he, if thats how you roll) is subject to a punishment up to the discretion of the latter party member

Adj. Something that is expected to have a long lifespan by virtue of having existed for a long time, based on the lindy effect, named for the New York restaurant Lindy's, coined by Albert Goldman and popularized by Nassim Taleb.