Drink like the bands.

Ex's, on the back of your hands
Wash them in the bathroom, to drink like the bands

These lyrics are most likely talking about a person in a bar or nightclub. If you are underage they put X's on your hands to signify that you are under 21. So this person obviously wants to be able to drink. The doorman put X's on this person's hands, or someone at the door.

So this person attempts to wash her hands in the bathroom so that he/she is able to drink and have fun while attending this nightclub/bar. This person is mostly a girl just as a stereotype or this person could be a guy. But looking at the previous lyrics it seems this person is a woman.Anyways, she wants to drink with the bands and probably get some sex out of them. She is a whore. If you look back at the lyrics they say "never trust a ho/Don't trust a ho". I think she is a whore.