So, in the end Alec did puke. Multiple times.
At 2am, when it was time to leave the bar, Alec chugged the last few sips of his beer. Then he started tossing his dinner into the pint glass, filling it completely. I grabbed him and rushed him into the bathroom where he went strait to the big sink that was more like a wash basin and filled it too. I tried to get him to a toilet, but he wouldn't go. Afterwards, Jared and I explained to him the ettiquite of drunk puking: just ditch the pride and go for the toilet, it's the right thing to do.
The next morning, before Alec went to school, he woke Jared and I to the (loud) sound of hurling for a second time. When I finally got up after he left, I found he had puked in the kitchen sink. Jared was slightly mistified that Alec didn't seem to understand what we had told him.
I guess then at school he puked a few times in the bathroom while Buddy waited outside. He was supposedly so loud that it attracted the attention of school security. The guard was cool though, Alec explained about his birthday and the guy helped him clean up and everything. Alec came back home with a red face from having burst his blood-vessels.
Anyway, Alec said that through it all he enjoyed himself a lot. Good work buddy, Happy 21st.