The term for a time during drinking when you suddenly need the toilet near constantly even if you have just been (also known as "breaking the Piss-barrier") Can also be applyed to non-alcohol related constant toilet trips but is mainly used describing when under the influence and alcohol is the cause.
Dan: Where do you keep dissapearing off to every 2 minutes.
Sam: Cant help it im pissing like a dentist!
Jason: Lets get in here.
Josh: Nah look at the queue lets go somewere else quick i feel like im gonna start pissing like a dentist!