Simply means Anal sex. It is derived from the fact that Spartan men were forced to bond using anal sex and anal sex is often used as a birth control in modern society.
"Dude, you gunna need a condom tonight?"
"Nah, I'm just gunna stick to good old Spartan birth control."
"Nah, I'm just gunna stick to good old Spartan birth control."
by kevin03246 November 19, 2008