What is the best lubricant for girls?

Durex makes great water-based lubes (Play, I think they're called) that are pretty cheap, although honestly ANY water-based lube is going to be just fine. Never get silicone as it's not good for condoms (breaks them down). Water-based ones don't irritate the either, which sounds like it'd be of utmost importance in this situation. And, of course, a little never hurt either. ;) Good luck!