The Science of “Breaking the Seal”

If you like beer, and like it in large quantities, this might be a familiar scenario: You sit down at the bar, get a beer and drink it. You drink another one. Maybe a third. Things have gone well up to this point, but now you have to pee. So you go. Once you return to your seat and keep drinking, though, it feels like you’ve crossed a point of no return, and you have to pee again and again.

What’s happening here?