At least 10 maybe one or two more. Wild high school party spent in a bathroom sucking off guys. There may have been a couple earlier in the day that I don't remember.
I love getting dp'd. It's the best orgasms you can imagine but you have to find guys willing to try it that aren't afraid of being around other guys that closely. Communication is important to coordinate the thrusting.
You should do what you feel comfortable with. That being said going out without panties or a bra looks and feels sexy and fooling around in public is so much fun.