While wearing a lab coat tell your lady friend to open her mouth and say "ah". She will open her mouth expecting you to put the popsicle stick into her mouth. At this point if you are doing it right she think you are into roleplaying a doctor/patient scenario. However this could not be further from the truth.
Instead quickly catch her off guard by inserting the popsicle stick into her pubic jungle. Then when she is about to climax put the stethoscope into her ears and fart into the other end. Bonus points if fecal matter comes out.
If done correctly your lady lover will be so grateful that she will probably actually start paying you to do it again. Celebrate this by drinking a v8.
Guy 2: Did you explain to her that it was just a one night stand?
Guy 1: Yes I made it clear to her. Do you think you can help me out.
Guy 2: Maybe you should punch her in the face.