AnnieHall's (almost) fool-proof advice on how to tell your S/O you're into tickling.
1. Bring it up early in the relationship. Not the first date, but early enough where you can end things if she's not into it. Tickling is really not that weird of a kink and settling for someone who's not into it, will suck.
2. Avoid the word "fetish." It holds negative connotations for vanillas. They'll equate it with obsession or psychological disorder.
3. Tried to hide being nervous. If you bring it up light-heartedly in a way that says, "I think this is really fun. We should try it some time," that mood will help to allay any fears the other person might have initially.
I think many women at that age are more comfortable with themselves and may be more open to trying new things. I could be wrong, but hopefully this helps.
Also, there was recently a gathering in Chicago. Unfortunately, the only female 'lees were both in their 20's, myself included. There's a chance said gathering may happen the same time next year. So, if you can make it, that'd be cool.