having sex with your partner's corpse after they reach twelfth base
I fucked this chick to death, and then I went to thirteenth base with her.
by 69Dildozer69 August 10, 2009
1 more definition
taking a persons urine in your mouth, then shooting it up their anal or vaginal hole.
Thirteenth base is hot
by sniff&sneeze June 05, 2010