Being specific, in summer when I see alot of women wear shorts. sandals and sleeveless tops. And we're (Australia) a hot country in summer, so anytime it's gets to sunny and 30+ degrees alot of attractive women dress like that. I might see them on the train or at the shops. I normally think about tickling their ribs/belly and feet.
And,
When I'm on the peak hour train going to/from the city, and there are hot women in office attire. Also, if their legs are in stockings and they are wearing high-heeled shoes that show the tops of their nyloned feet.
I know you can't see their soles, but when I see a good-looking woman with nice feet in nice shoes, those formal heeled sandals or business "heels", I think how much I would like to tickle them, even the tops of their feet.