Last week, swimming lessons.
Sat down at only availble table next to H. Shared it with a woman with a child in a pushchair, and one on her knee. Older child was in pushchair, with a box of raisins.
This is after 10 miniutes:
Me: I think your son has dropped some of his raisins on the floor (smiling)
Her: What business is it of yours?
Me: None at all, except that I'd think about the next person that sat there, and clear them up.
Her: There are plenty of free tables over there.
Me: Yes, but both my daughters are taking an exam today, and I'd like to watch it.
She left, and I don't think I' particularly anal, but I asked them to sweep them up. Thought stamped in raisins would be nasty for them to clear up, as well as anyone who happened to tread in them.