The popperkeg is a small percussion instrument that plays entire melodies from a single note by emitting a thumping sound when slapped with the palm. As the keg clasp is moved rhythmically back and forth along its tubular body, the popperkeg's pitch raises and lowers accordingly. Whole melodies played on the popperkeg are often variations of just one note. The popperkeg is popular among the very young, and those who refuse the commitment of a two-player instrument.

In the Z'Orchestra, the popperkeg is positioned in the back row, strage right. To their left are the frobophones and before them are the fleezles.