Friend uncontrollably rapping/rhyming when drunk

Not sure if this is the right place but I wanted to ask about this

Let me preface this by saying we’ve drank before many times over the years and he’s never done anything like this. He’s usually pretty calm even when we drank a good bit.

The other day my friend had like 8 shots of lemonade vodka in less than an hour before I cut him off, and he started non-stop loudly rapping for more than an hour before he finally stopped because he was vomiting everywhere.

I mean non fucking stop. EVERYTHING he said rhymed. No matter how many times we told him it was late and that another friend was sleeping in the other room, he just wouldn’t give up. He’d genuinely apologize and get quieter for a minute or two (still rhyming) but then get loud again. It seemed almost uncontrollable. He’s always been a calm, rational and level-headed person, and never one to be annoying, but it seems drinking that much made him lose control. It seems crazy to say but it to me it felt like a side effect of a mental health issue or something. I straight up couldn’t believe what was happening.

It sounds hilarious but from my point of view it was genuinely concerning. Like he physically couldn’t stop himself from doing what he was doing

Has anyone else experienced something like this before?