1 definition by -mastablasta-

When someone has constipation, they used a large black penis to open up the rectum and increase flow of feces.
Person 1- Fuck me! I can't take a shit.
Person 2- You've got constipation, you need a blaxative.
Person 1- Whats that?
Person 2- Big black dick up your ass to widen it so you can take a shit.
by -mastablasta- June 23, 2010
Get the blaxative mug.