What is his problem/motive? Is he trying to call attention to me?

UGGHHH I hate guys like that, I guess you just got to give him the cold shoulder and he will leave you alone, I worked about 3 similar jobs like that and well the 1st one I didn't do or say anything because I was young and didn't really mind the attention until the sick cornered me and stuck his hand up my shirt when I had to scream to get away! Then I had a painting job and the shift supervisor would always follow me outside and smoke with me even when I would go to the bathroom he would be there waiting for me to come out, it freaked me out, well I didn't want to piss him off so I just gave him the cold shoulder and wouldn't talk to him and he left me alone after that, this is the best thing to do you say your a lot younger then you need to stay away from him, and if he don't stop then you need to straight up tell him hey dude I'm not into you so back off!