When in the act of masturbating, to ejaculate with an upward thrust so hard that the semen barely misses the eye.
"Maks, what did you do last night with Gary Chelnis?"
"Yo, I blonched with Gary son! You ain't fresh azimiz!"
to suddenly turn red in the face in a moment of sudden embarassement; redness
-When the girl sat on his lap, his face blonched up.
-She's got blonch on her today. (reference to what she is wearing.