Favorite ot4 flavor is f/f/m/m who are originally two "straight" couples. One is "we're straight and monogamous, we've been through life together and content with how things are", the other is the "we're straight-baiting everyone in the vicinity bcs we're horny bisexuals looking for milfs and dilfs" couple.
Even better if the "straight" couple is older and "we're straight-baiting bisexuals" couple is younger.













