funny interview

Kind of funny story.
I interviewed in the London office of a Swiss bank w/ BS in the name.
I had MBA associate full-time interviews going all morning and things were going pretty well.
You can kind of feel when the tide has turned your way, and that the teams have already chatted internally, you're 80% towards getting the offer, and now they're just validating each others' favorable judgement.
The MD who ran the group interviewed me last.
It had been a long day, and so he said "would you like some water."
Me: "sure."
OK well it's over there. Get it yourself.
I went over and they had those glass bottles with the metal clasp on time (mason jar type; the kinds that Ikea sells).
I opened it, and it exploded.
I got a full-on seltzer water facial money-shot, and was pretty much drenched.
The MD had taken the seltzer bottle, and must have spent 30 minutes shaking it up.
He laughed, and said "So what did you learn?"
Me: "Never to accept any drink you offer."