i don't suggest you beat it before class, it will reduce the free testosterone in your body and will wind up affecting your mat performance.
wear a cup, sex should be the last thing on your mind while doing jits. I was put in a figure 4 headlock while rolling no gi with a beginner girl. She tried going for a triangle but forgot that she needed an arm, it wasn't even around my neck but my face.. I got a face full of gross pussy stank from an unattractive girl, nearly gagged and felt pretty uncomfortable being around her after that. She was wearing mesh shorts and sweating profusely... disgusting.