He goes in the shower over a brunette and rubs her clitoris means that he is in the shower with a brown-haired woman and stimulates her clitoris. This implies a direct sexual action, in which he pleasures her by rubbing, perhaps with his fingers or an appropriate object, on her clitoris, which is a very sensitive and erogenous area in women. The scenario suggests an intimate and erotic situation where he uses his skills to give his partner a pleasurable sexual experience.