If you see someone that has “not a unicorn” statement in their bio, it means they are unwilling to have a threesome. A unicorn is “bisexual girl who is down to hook up with heterosexual couples”. These are single girls that will be willing to hook up with a couple. You have likely seen many that say they are “not a unicorn”. This basically means they want a male or a female but do not want to be in a threesome.