Funny Joke

Here's a joke a friend told me:
So there's a man and a woman in a bar and the man turns to the woman and says "Hey, I've got this magic water that can make me fly." Then the woman says "I don't believe you. Show me."
So the man downs a magic water and gets on the top of the roof, jumps off, and flies back on. The woman says "Wow! Do that again!"
And so the man goes back downstairs to drink another magic water, gets back on the roof, jumps off, flies back on. The woman says
"Whoa! I gotta try that for myself!" The woman goes downstairs, asks the bar tender for some magic water, drinks it, gets on the roof, jumps off, and dies.

When the man comes back downstairs the bar tender says to him,
"You know Super Man, you're a real jerk when you're drunk."