Say it loud
I'm black and I'm proud
Say it loud
I'm black and I'm proud!

Except that halfway through the infectious funk, the crew-cuts realize what they're saying: Jesus christ, 'I'm proud to be black' fer chrissakes, like when you're in the porno store, you know, and you get lost or something and you find yourself in the men's part, you know? not the part for men the part about men, Jesus, and you get the hell outta there. And so they hum/mumble the suppressed parts

Say it loud
I'm mmm hum proud
Say it loud
Mum hum hum proud!