Have you ever played with helium and made yourself sound all funny?
I was doing this today at work but I accidentally sucked in too much out of the balloon apparently (until today I didn't know this was possible) and almost fainted. For the next three or so hours I was dizzy, had a massive headache and couldn't hear or see correctly. I promptly went into hypochondriac mode and started looking up the dangers of helium via google and getting scared that I'd permanently damaged my brain, etc. Oh man, I'm starting to feel dizzy again...I'm scared.
So umm, yeah, do you play with helium? If so, just say no!