Fart rolling to the front
When I fart and are sitting in an awkward position, The farts will roll up to the front. feels weird, like bubbles plowing through my cooter and out the top. this mostly happens to women like me and it's worse during the period because it creates blood bubbles and it's harder to pop without aggressively squeezing legs together, depending on if they are wearing a pad or not. It's most likely not going to occur if they are wearing a tampon, but a pad... not a great feeling.
I've heard that it does happen to some men, like how a fart rolls up and gets trapped between their sack and leg.