I remember a wonderful little incident from one of my own teachers. He was in his early forties back then.
He was our physical education teacher, and once every two weeks we would go to the local pool for swimming class. One time, I remember him being nervous and fidgety on the bus ride towards the pool, which already made me suspect something was up. When we came to the pool, he jumped out of the bus and waited by the door until all of us were out as well, and as I descended and walked past him, I noticed he quickly grabbed his crotch and pinched.
Dressing into swimsuits was with all of us in one big room, and the teacher had to wait next to this room until all of us were done. To change, I had chosen a position from which I could see him through the open door, and as he was waiting for us, not aware that he was being watched, he was constantly shifting from foot to foot, crossing his legs; basically doing a pee pee dance.
Once we were in the pool, he quickly had to take of his training suit, under which he already wore his swimsuit.
When he came into the pool area, he immediately jumped into the water with us, were he had to show us some swimming techniques. But since I was watching him, I had seen, before he jumped into the pool, that he had a wet spot on his swimsuit.
I have never known what exactly happened : did he not shake off properly when he took his much needed pee in the toilets that were between the dressing area and the swimming area, or did he leak before he got to the toilets? Since he was obviously desperate, it could have been the latter option.
But of course, I couldn't really ask

)
Have never forgotten it though!