Doing some Christmas shopping today and I am waiting in line, items on the belt.
I glance down, turn to the gentleman behind me in line and say:
"I'm sorry if this sounds like a strange request, but would you mind if I felt your ball?"

As I asked, I was pointing to a dog toy he had on the belt - a tennis ball with a rope attached.
He just smiled and said go ahead, whereupon his wife and I talked about the merits of the toy and I decided it wasn't suitable for my dog.

Later on of course, I thought if 20 better ways to phrase the request, but by then it was too late.