I don't know what I'm supposed to do?

I'm 16 and I work in an heavily male dominated area. There is me and another female working with at least 25 men, there's one toilet for all of us. Me and the other female are rather hygienic. But at least twice everyday when I go into the bathroom there is always urine on the toilet and floor, pubic hair too. Today someone had gone to the bathroom, pissed all over the toilet and floor and did not flush the chain, what am I supposed to do? Why do these grown men think this behaviour is okay?? I'm so sick and tired of been expected to clean this mess up when it shouldn't have happened. I'm disgusted, it makes me feel uncomfortable, what am I supposed to do? Talk to the boss? Ask the guys to clean their act up? How would you deal with this?