when you are talking to your friends about the night you had with your girlfriend before finishing with a sexetera meaning you did more sexual things with her
JOHN- hey jake tell us what you and your girlfriend did last night
jake- well i licked her tits she sucked my dick i ate her tight pussy (SEXCETERA)
John: "Dude, I fucked Sally, but she said I had to keep it a sexcret."
Ted: "Had to keep it a what?"
John: "A sexcret, secret sex."
Ted: "Good job."
John: "Oh Fuck."