Personally I've never had an issue but a bloke I worked with had either large or low hangers and we would often here him cursing to himself after sitting on them. I remember this one occasion when I was an apprentice me and this other lad had to attend a breakdown and recover a bus back to the depot. Back then we used to have an old bus converted so we could tow vehicles back with it using a bar. So we're in the non running bus being towed and he was behind the wheel steering etc and there was an incident that meant he had to brake hard. So when doing this he lifted up off the seat allowing his balls to move into a perilous position, so when he released the brake a came back to sitting he had trapped them. I've never heard a noise like it and caused him to let go of the wheel meaning I had to then take action to gain control again. Scary at the time but how the lads laughed back at the depot when retelling them was brilliant.