It always happens to me after doing it from behind, especially if the guy is doing this weird kind of thrusting, like pulling out almost completely and going back in really fast... I can usually tell that the air is trapped up there, and avoid bending down for the rest of the booking lol and then let it all out while they're in the shower
So you CAN hold in a qweef! You have mastered it lol!
Sometimes I can, I think I must have a really weird vagina
although obviously I can't control it all the time, and do a lttle 'fart' in front of the client, not that I care either way he he!