Any extra income earned from sucking dick, performing fellatio, smoking the pole, playing the skin flute or whatever YOU and your click may call it. This type of income is generally not from your primary job/career rather, from blowing crank on the side.
Edgar: Damn girl! How can you afford such a nice ass car on your minimum wage job?
Evelia : Oh, I've been earning a sucklemental income on the corner of Guadalupe and 17th by gargling meat sticks.