From one of my childhood trips Down South. My cousin (I don't remember now if it was Rudy or Brother) did this dead-solid-perfect imitation of this old black watermelon-seller in the neighborhood (in a small rural town), who would announce his wares with a simple chant.

Wawwwwwww - tee - mel - un - waw - tee - mel - un - waw - tee - mel - UN!

And thinking about it years later, I realized that it sounded more like Native American music than it did any form of the blues.