here is a generic boyfriend destroyer that I use all the time when a girl tells me she has a man. "That's awesome, (pause) he can clean our house and watch our kids when we get married" That's one that David Deangelo deserves credit for.
The purpose of a bf destroyer of that type isn't to magically make the girl want to break up with her girlfriend, rather it serves to show that you are unaffected by her objection to your advances and it also demonstrates a strong frame.
Usually when I use a cocky funny type bf destroyer, the mood of the girl im trying to talk to is a lot different the next time around.
Remember, It is important to realize the reasons a girl would bring up her boyfriend in the first place. 90% of the time, the only reason a girl would mention a boyfriend to you is if you displayed too much attraction. For example: If you run bad game, a women whose not attracted to you can mention a non existing boyfriend just to ward you off. ON the other hand, if you run solid game, she may not mention a bf even if she DOES have one. The other 10% of the time, a girl will tell you she has a bf just to take the guilt off of her for anything that happens moving forward.
Ross Jefferies has some interesting bf destroyers designed to plant a seed of doubt in the girls mind about the man she is dating. I personally don't use any of Ross's dirty mind rape NLP shit but you might want to look some up.
Ultimately, the point is this: Whether a girl tells you she has a boyfriend or not is irrelevant, it usually just means that you telegraphed too much interest too early on. YOu need to be unaffected by it and you need her to feel that you are unaffected by it. That's the only way to keep yourself in the game
game on fellows