Although I don't get a chance to go much anymore, the beach was always a great place for foot watching.
I only tickled a stranger's feet one time and that was by total accident.....
To make a long story short, I went with a group of friends and after about half an hour, I saw a woman sitting not too far away. It looked like a friend of mine who I knew had VERY ticklish feet.
So, seizing the moment, I crept over to her and tickled her feet for a few seconds.......after a "What the hell?!?!?" and a few embarassing moments and an apology later, I "crept" back to my friends.
One interesting note....two of my female friends who were with me witnessed the entire episode and decided to tickle MY feet to teach me a lesson which was FINE by me. =)
Anyway...just my two cents....
Impaler