Absolutely fleecewife.
It may be normal teenage hormones making him stick it out, or may be a bladder blockage.
Please make sure he is peeing ok Asap as it is an emergency and can be fatal if he can't pee.
Sheep hide illness very well, so the bladder can rupture inside before they seem unwell.
If you watch him pee with normal frequency, good steady stream and normal colour and consistency then it could just be him enjoying himself, but please check the former before putting it down to that.