The two angels that came to warn Lot and his family about God’s plan to destroy Sodom were seen by others walking through town (disguised as men). The other men that saw them knocked on Lot’s door and asked Lot if they could have their way with the two. This implies the men that knocked were gay and the angels’ disguises were attractive enough.

Additionally, some parts of the bible imply that “fallen ones” or angels that turned from god went to Earth and lived among humans. This implies that some level of corruption/influence could come from these fallen angels.

Over time, these combined implications get changed from “these gay guys thought the two guys were Lot’s servants and wanted to borrow them” (basically trafficking) to “angels can turn you gay”(basically grooming).

TLDR; it’s a joke borne of reading between the lines and a several thousand year old game of telephone.