Descartes and the Drink

I'll tell you an old Descartes joke,
That you won't get if you're a slow-poke

Descartes was the one that said,
I think, therefore I'm not dead.

Actually, it's I think, therefore I am,
I just inserted 'dead' to get out of the word jam.

Anyhow, so old Rene once went to a trendy bar,
That was known far and wide as Drunkman's Star.

Now he'd personally never yet had a drink,
Though all his friends regularly downed and went off the brink.

So, anyway, to this bar he went,
And called out, hey, a drink for a gent!

The bartender took one look and thought him underage,
He certainly didn't want to deal with that kind of legal baggage.

So he said, you can't get a drink here,
Why, we don't even serve any ginger-beer.

Rene didn't swallow such an obvious lie,
He got up and glared at the big guy.

He shook his fist and shouted, "I don't think..."
And, poof, therefore stopped existing before he got his first drink!