When Maxx and Cyril go caving they meet skeletons.The first encounter was in comic #50, when Maxx spits in one's eye. Maxx accidentally destroys it later by causing a copper vein to fall on it which is shown in comic #79.
He uses the Hammush against another one, knocking off its skull and creating Skeledeath. They are captured by skeletons later on, and held over a lava pit in comic #95. Also, their livers are swapped by a skeletal enchanter.
Jaal gro, fen pu'taal! (Death to the eye-spitter!)
Grah. Grah? Grah! (Standard skeleton words.)
Baal! Ra gro shon blak draal? (Angry skeleton exclaimation. Probably "Roar! Who spat in my eye?")