Clarence Reid (aka Blowfly) is paid to do things that get creepy uncles banned from the kids table. Since turning out 1965's "Rap Dirty," reputedly hip-hop's first jam, he has straddled the line between novel party starter and warped sex criminal, making his name on such tender classics as "Shittin' on the Dock of the Bay" and "Porno Freak." Now in his 60s, Blowfly still rocks the trademark mask and sequin cape, turns out his special "party records" on Jello Biafra's Alternative Tentacles label, and knows, as he always has, "What a Difference a Lay Makes."