i just usually pull it out and say "what are we gonna do about this?"
But I would say this depends on location.. If you're in the car, just start kissing her and put her hand on the bulge. Then unbutton and have her spank it for a little bit. Then ask her to "kiss it." say "you dont have to put it in your mouth, just kiss it" then when she does it, fake a moment of exstacy and tell her how her mouth is velvety soft. Then ask her to kiss it again. After like 5 minutes of boosting her ego and taking away any self esteem issues she may have. Then ask her to go a little deeper. Before she knows it she now went from kissing it to a full fleged blowjob. Thats the trick.. You cant let them think about what they are doing or they will feel dirty and their conscience takes over and reason prevails.
Works like a charm
Duke