Sketch on

To sketch on someone is to hit on someone and attempt to seduce them. Using the term "sketching on" rather than "hitting on" or "flirting" generally implies that the sexual advances are inappropriate or unwanted.

Prof. Watkins always tries to sketch on the girls in his class, and sometimes they hook up.

Sketch on by Octarine May 27, 2008

on the sketch 

a cooler, hipper, more chic synonym for the word sketchy.
used to describe anything that appears amiss.

"dude, i don't know if we should get high. this place is on the sketch."

on the sketch by bear capitan July 2, 2009