So Bad is an Eminem song in which he talks about how he is good in the sack
"Soon as you wrote your number on that napkin, I was bound to work a number on your back
and throw your spine out of alignment
"So good, so good that I'm so bad, I guarantee
I'll be the greatest thing you've ever had, cause you aint
never met nobody like me, and you aint gonna wanna fuck
anybody else again"