Giving foot and or boob jobs with 2 or more people.
Dude, last night i got to 12th base with this hot chick and her twin sister!
To defy the laws of physics whilst engaging in sexual intercourse.
A common example is to have sex listed as the 'Bat Position' in the karma sutra, and that is to have sexual intercourse on the ceiling.
I went to 12th base last night and i got such a rush to my head.
A sexual act including a saddle and/or table tennis paddle
guy 1: we got so far last night
guy 2: what base
guy 1: 12th base
guy 2: Woah!!! how did u get a saddle into her car
Fucking a chick so hard that she dies.
Man 1: Ah shittt man, I fucked Cindy so hard, I got to 12th base!
Man 2: FUCK! Where is the mangled-sexfilled-corpse?
Man 1: In my car where I left her...
Man 2: I say, go for 13th base
Man 1: Ahh, wanna munt
her with me?
Man 2: YEAAHHHH, I'll jump.
When your girlfriend removes her glass eye and you prodceed to insert your penis inside the hole and fuck her.
Guy 1: "Dude we got to 12th base I don't deserve to live anymore."
Guy 2: "shit bro I'll get my bat."