It's tricky. Where are you hoping it will lead? I used to try this as a teenager. I used to say things like It's weird how you can't tickle yourself. Not saying it was a good idea, but it's what I used to say. People aren't generally too interested.
I will give a girl a quick tickle while talking to her then say aren't you ticklish ? or oh your ticklish , I am too ! do you hate being tickled ? I wont do it if you hate it