Your heart pump project Kool-Aid, you're sweet
Saying that someone’s heart pumps Kool-Aid is a way of saying that they lack heart — that they’re weak or cowardly. Calling someone sweet implies that they’re gay or soft. Jay is basically questioning Nas' masculinity here.
Also plays on the stereotype of kids in the projects adding masses of sugar to the drink, making it super sweet. Remember that scene in House Party?
If you haven’t seen the film, the kid pretty much pours the whole bag in. It’s one of several gags in the film about people who live in the projects.
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