You turn the flashlight to its brightest male setting. "Hi Melissa," Gene says, "Pete here was just asking about my vagina."
You hold the flashlight against Gene's arm and, while aiming at Melissa's crotch, you quickly turn it on and back off. You quickly put the flashlight in your pocket again, so neither of them realize what just happened. "Yeah," you say, "I was wondering how it must feel like to grow up with one."
"Well, then Gene is the right person to ask," Melissa says while giggling, "I'm often curious about it as well."
This reply confused Gene a bit. "Why would you be curious," he asks his girlfriend, "you should know just as much about it as I do."
Melissa smiles and replies, "Well, I guess so. We have been dating for a long time now, and I guess my situation helps me understand as well."
You look at Melissa's pants and notice her getting hard. Gene, however, still hasn't realized that his girlfriend now has a dick. Your plan is going just perfectly. You decide to try a similar thing but in the reverse, keeping the flashlight on bright blue, holding it against Melissa's arm, and shining it on Gene's crotch. Gene doesn't notice his penis growing back, not even remembering he ever "lost" it in the first place. You put the flashlight back in your pocket as Melissa says: "we're a bit of an unusual couple."
Gene doesn't know his girlfriend has a penis, while Melissa thinks her boyfriend has a vagina, which doesn't. This is pretty hilarious.