This happened a few days ago but as it is still making me shudder when it decides to jump into my brain, I thought I'd post it.
There is a regular customer who comes in and knows everything, he's always giving me the "keep away" vibe so I do my job politely and don't engage him at all. Recently he's been trying to chat to me and try and be amusing (his idea of amusing is putting others down and trying to tell us our jobs) but I have continued to give minimum responses.
The other morning he comes in to pay for his fuel and then decides he want 10 cigarettes as well so I ring them up too while he counts out the extra money. Then instead of just handing it to me he tips it into my hand making sure his fingertip slides along my palm, my stomach turned and it was all I could do to keep my hand still. I wish I could say it was an innocent gesture but the smirk on his face afterwards told me all I needed to know. I have no idea why he has picked on me to be his target, there are other more attractive women working here, in fact all of them are, than me.
If he does it again I am jerking my hand away while making my apologies.
Edit: Just to say thank you for the lovely replies and support. You have been really kind.