Similar to 'Thats what she said' but more sophisticated grown up, party slang. Used especially when alcoholic beverages are involved and they are disguised in red party cups.
When a group of guys or girls (Not both at the same time) go all the way with each other in a dark room with red lighting. There is usually leather outfits involved with the sexual play.
A Red Tent Party (named for the book The Red Tent, which features the Biblical character Dinah) is a party held in honor of a girl's first period. Uterus and period-blood themed food and decorations are appropriate.
Janet: So, my daughter finally got her first visit from Mother Nature last week; now we get to host her Red Tent Party!