There are a few ways to get a good girl to go bad. There are also a few ways to get a girl to go bad with another girl. This is especially spicy if the girl is reluctant at first, but then she just simply gives up to the sinful feelings. Have you ever managed to convince your girlfriend to have you fuck another girl right next to her? Though, if you didn't manage to do it (and honestly most girlfriends won't like that kind of thing, so it's completely understandable), then you can get your experience in FFM threesomes from porn, which is also completely fine. However, some girls want to be dicked down by two men at once. Seriously, they can't settle with one cock up in their body, so they'll want to have one up in the mouth or the hand, and another one in their pussy.