I've been called Ernie since pre-school, when my parents thought I needed an American name. My mother had seen Sesame Street while she was working on her English, and she really liked the character of Ernie. I'm not sure why she liked the character, but that name has stuck with me since then. So yes, I was named after a puppet.
I rarely use my legal name, except for paperwork and things like that, and I generally don't introduce my self as Ernie, a.k.a Young. People usually get Ernie, and then they're surprised if they ever see my license or what not. When I was getting carded somewhat frequently, I did make an effort to tell my friends my name, so I wouldn't have a bouncer thinking I was using someone else's ID, as people would call me a different name than on the license.
The few people I meet as Young tend to be doctors, dentists, insurance agents, etc. The people who get my name from some paperwork, and I figure I'll have limited interaction with. In most of these cases, I tend to be in a hurry, and don't feel the need to say "Oh, call me Ernie" to them, their staff, etc. Now, if I'm smart, when I call and make an appointment, I ask if they have a nickname field or whatever, and make sure they get Ernie in there.
The other group that might know me as Young are grocery store checkers who ask for my ID when I'm getting some beer or wine. Most of them don't even look at the name, but every now and then there's the one who says "well, I guess you'll always be Young!" . . . because that pun never gets old . . . *sighs*