This is generally a censor of the word “trap”. While it obviously has several non-slur meanings, it is also used as an extremely visceral anti-trans (and in particular, anti-transfem) slur :/
The implication is that transfem people are “secretly gay men trapping straight men into being attracted to them”. It is associated with simultaneous sexualisation, homophobia, and transphobia >.<. If someone called me that IRL I would be seriously worried for my safety, as that’s often the kind of thing people would say before either raping or killing or injuring a transfem person for “”“threatening”“” their fragile sexuality, then using the trans panic defense.
The term got it’s start on 4chan, and people used it for femboy characters in anime (who are often poorly translated and may actually be trans in a lot of cases), but the kind of dehumanisation aspect of it means it very very quickly became a viscious anti-trans slur :/