I sort of already designed one unexpected trap in my story where boys lose their dicks while trying to fuck corpse of the girl :)

>>808
I think abstract "machine" is a bit too ambiguous and it is hard to even imagine how it could happen without some use of magic or ultra advanced technology.

But by following your idea I came to this:
that there is a typical setting of a girls stuck in the wall. with her butt fully open and available and when as usual some guy comes to fuck her he gets trapped too now getting his ass exposed for others at this point I think it turns into Gay trap :) Unless that character was Futa.


More realistic design would be placing a bottle of lube next to the girl but rather than a lube it is superglue :) and rather than being stuck in the wall the girl is laying down on the table because she got stuck with that glue.