Tim_Tex. If you can't fit in with other South Park and Simpsons fans, it is probably because you're a Christian and these two shows and their usual fan bases are VERY anti-religious.
Examples: Jesus being in Imaginary Land in South Park.
Reverend Lovejoy telling Flander's, "Oh Ned, haven't you tried any of the other religions? They're all basically the same."
The Creationism vs. Evolution episode of The Simpsons.
I could go on with this list, but I won't. I hope you don't see my statement as insulting your religion, because I'm not trying to. I'm just stating how anti-religious these two shows are, and how fans of these shows are usually anti-religious as well.
As for keeping interests to myself, I usually don't. However, when I do reveal them, I end up becoming a laughing stock. During my Junior year of high school, I started telling people about my Godzilla obsession, and 95% of the whole school teased me about it until I finally graduated. There was this one idiot who constantly made fun of EVERYTHING I was obsessed with, and just wouldn't shut up. Being the pacifist that I am, I had him sent to the office. He never made fun of me again (or at least not in front of me).