Back in my younger days, I'd just grab a girl around the waist or under her arms and tickle away (usually followed instantly by squeals and hysterical laughter). Of course, this was a little risky....I've recieved a couple of keen elbows to my gut from out of control, very ticklish girls 😀
Another great idea for a quick tickle is find a girl lying barefoot, and tickle her feet, knees, etc. I've done that to my girlfriends, my oldest sis, and her female friends many times as I grew up. I loved it when my little sis use to have sleepovers/ slumber parties....nothing was more fun than 6 or 8 ticklish teen girls in the same room, all lying asleep on the floor with their bare feet at my mercy. Only problem I had? Who's delightfully ticklish feet to tickle and tease first? 😀