No seas fresco!
I came up with this but I am not sure you can use fresh this way.
First: In English when, someone says, "don't be fresh," they are making a protestation at somebody's behavior (including unwanted advances) which they considered to be rude or unwanted in that it is unabashedly bold, cheeky, saucy, impertinent, shameless or impudent.
Second: This definition coincides completely with what has already been stated by Marianne. The RAE describes this as "desvergonzado," a term which certainly could be applied to the situation to which you refer.
This has been discussed previously on another forum. You might be interested to see what was said there regarding the use of "fresco" in this context: Fresco
Not exactly what you were looking for...but I got this from another dictionary:
(=descarado) cheeky, sassy (EEUU)
¡qué fresco! what a cheek!, what a nerve!
¡usted es un fresco! you've got a nerve!
Let's see what the native speakers have to say about "fresh" being a person who makes unwanted advances.
I'm pretty sure that says Not you fresh: You are not fresh.