r/StraightGirlsPlaying has 867K members watching girls who identify as straight fooling around with other girls. The appeal is the curiosity and experimentation. Straight girls kissing, touching each other's tits, going down on each other "just for fun," or having their first lesbian experience. It's not full-on lesbian porn. It's that grey area where supposedly straight girls get a little too handsy with their friends after a few drinks. The amateur, "oops we went too far" vibe is what makes it hot.