How can I deal with this? sexual harassment?

So you're 21, female, and "work as a bar and gaming attendant at a pub that is mostly frequented by seniors and older foreigners" and you can't handle when old men say sexual things to you? Hm, I think what you can do to remedy this issue is go get a job doing something completely different, and perhaps study up on socio-biology a bit?

To your last q: Ya, be less insecure and less sensitive about stuff that doesn't matter; learn to roll with it and be a big girl. Life is going to get a whole lot rougher than some guys acting sexually toward you *gasp*