>>3655312here is the answer
idk where that akbar trap meme was first posted, but it was on forums before /b/ was ever around
there was that variant with the asian trap in a swimsuit also
anyway, once you had the beginning of the e-celeb/camwhore culture in the mid-2000's, a lot of convincing guys in drag started trapping people and the term became really popular
this led to actual trans women who would frequent places like /b/ getting called traps and becoming pissed
this then evolved into good natured ribbing where you would call a trans woman who could pass a trap to intentionally make them mad - eventually most took it as a compliment and were in on the joke (and begging for viewers on their streams/tokens)
some trans women still aren't in on the joke and get mad when you call them traps tho and a lot of younger kids who use the term don't even know it's a joke and call them traps unironically (I should go update the KYM page on this at some point before I forget all the history)