'Paul's Law'
1. a notional, Internet-born law (example: Godwin's Law) which dictates that any discussion--irrespective of its subject matter--will eventually become "derailed" (*moved off topic) into a debate about "traps" (*male-to-female transsexuals); in particular, whether or not an attraction to / relationship with said gender denomination
by males is considered homosexual.
(NB: In this sense, the law pertains only to "pre-op" (*pre-operational) MTF trans girls.)
2. an expression indicating that a given conversation has veered away from its original topic and into the realm of "traps".
Etymology:
The nominal reference pertains to the Hollywood action film B-actor, Paul Walker (1973~2013). Subsequent to Walker's death in 2013, an un-authored "dialogue meme" (*series of pictures, generally taken from film, with subtitled captions) appeared. This meme comprised a sequence of images depicting Walker with another action film B-list actor (Vin Diesel) -- images taken from the final, tributary scenes of the film, Fast and Furious 7 (2015) -- engaging in a debate on the topic of "feminine penises" (*the 'femininity' of "trap" genitalia as viewed by their aficionados).
The can be viewed here (*SFW): Oqm33CQ (imgur website)
The proliferation of this image is largely attributable to the 4chan Internet image board and its denizens; in particular from its notoriously "trap-happy" sub forum, /pol/ (political)--wherein the notion of 'Paul's Law' is oft invoked or 'proven'.