Very true!

Dude just because a strip of your skin is showing does not mean that you're a "slut"

I think he is referring to the excessive amount of makeup that child is wearing. Then again, times have changed.

don't understand how wearing an excessive amount of eye makeup makes you a 'slut'.

Its an (understandable) stereotype. They dress more and more like grown ups, showing skin, excessive make up, tight dresses, bare leg, blah blah blah, and being from their generation, I can confirm they spend alot of time "doing things" with boys.