Why are guys always teasing me?

I work at a fast food placw with all guys. I only work with two other girls. Its mostly guys and we cook in the back. The guys are ALWAYS teasing me! They pull my hair, squirt water on me, imitate me and ita embarassing becausr they always tell me things like my bra straps arr sgowing. They always teasr me and say that Im their girlfriend and beg me to go out with them. Are they beingean and making fun of me? Im the omly girl they teaee and im shy. Am I some dork to them? What do I do?