Visto che siete un po' scherzosi sul tema, vi posto la definizione che ho trovato su wikipedia:
An egg shaker (also called in Italy "uovo sonaglino") is a hand percussion instrument, in the idiophone category, that makes a noise when shaken. Functionally it is similar to a maraca. Typically the outer casing or container is ovoidal or egg-shaped. It is partially full of small, loose objects, such as seeds or beads, which create the percussive sounds as they collide, both with each other and with the inside surface of the container. The egg shaker is a Latin-American instrument, cheap to buy and relatively simple to play.