Kids and parents asking to use my paints???

It's okay to be firm, but polite, with people who are stupid. And in the end, it's really okay if she doesn't like you anymore for not letting her use your paints.

Your insurance will not allow it, Period. Shannon has a great sign about judging the wait time. People have a choice to wait or not.

I like the toothbrush comment. Clever.

I think when people do this, you should definitely stop what you're doing and totally confront them. They need to see that you're saying no with your body language, as well as with your words. Once everybody sees that they're holding you up, the others waiting in line won't be too happy.