The cuica is a friction drum of African origin played in the batucada (an ensemble of instruments used for the samba) during the Brazilian carnival. It is played by rubbing a bamboo rod which is connected to the center of a drum head, giving a rhythmic grunting sound. Pitch is changed by applying pressure to the membrane. This paper discusses several acoustic aspects of a folk cuica (made of a gourd) including the waveforms, spectra, and time envelopes produced. Rubbing the bamboo rod gives a primitive saw-toothed excitation, similar to a bowed violin string. This is connected to the center of a membrane which modifies and radiates the sound. The body of the cuica contributes little to the sound.