Okay, two things for me:
1. This.
He stares into your soul. I wanted to get a 64 SOOO bad as a kid... but it took me a year to finally get over that face. Even though my parents were totally willing to get one for me right away.
2. A specific Captain Planet episode.
I originally wasn't going to say this one, but considering some of the other responses so far, I don't feel as bad about this now.
There's an episode of Captain Planet where most of the team gets shrunk down to microscopic size, and Quami drinks them in a glass of water. While inside him, they get attacked by... something. White blood cells or something like that, I can't exactly remember. This scared the crap out of me.
I was afraid of either drinking someone, then having them grow to normal size inside of me, causing me to explode, and of being drank by someone, and attacked by microscopic organisms.
Weird one, I know.