A sex act involving 2 or more people where picnic style foods (apples, crackers, sandwiches, cheese, dip, etc.) are shoved into one participant's anus thus making him/her the "picnic basket". Everyone then proceeds to have sex, orgy style on top of a red-and-white checkerboard patterned blanket that has been laid under a tree on a grassy hill. After the group orgasm each person takes some food out of the aforementioned picnic basket to munch on.
*Note: 2 or more people need to be in attendance, sticking food up your ass and masturbating does not count.
"Jill and I were planning our own little Forbidden Picnic but on the way we met a homeless man which made our Picnic all the better."
The sexual act of engaging in anal sex while eating food off of the receiver's back.
The grapes tasted so much better eaten off of Jessie's back during the Forbidden Picnic last night.