It's a like the food chain, or the evolutionary chain, but for fucking.
Can be used to refer to the hierarchy of
sexual experience (losing your
virginity, losing your orgy-virginity, losing your gay virginity, etc. in some kind of order #progress), or the hierarchy of taboo
exploration (heading towards more perversion, worse taboos).
Or as a slang of a slang, it can be used to refer to things as a fuckchain, like saying fuck this or fuck you, but referring to work as a fuckchain, or saying you came from a really weird fuckchain.
You've got to fuck up the fuckchain (meaning fuck older partners), to gain experience.
You've never really entered the fuckchain until the ones you fuck fuck you.
My fuckchain has a fuckchain (meaning my child just lost their
virginity, or had a child, or that my partner cheated on me, or referring to
fucking someone who didn't lose their
virginity to you).