Soustroumpf

In the Aeon of the Champion story series, Soustroumpf is the name of the language spoken by the undertrolls before they evolved into smurfs. This was a lower form of troll discourse, which was already rather broken in flow due to the relative barbarism of the race. The undertrolls, considered a lower form of troll already, spoke this language during their Days of Affliction when the other troll tribes ruthlessly pursued them across Old Vigrith.

Even after settling on the Cerulean Plateau and becoming intelligent beings, the smurfs continued to speak in Soustroumpf from time to time (when they weren't speaking smurf, and named their sons and daughters in this language. The practice continued until the War of the Ancients, after which, similarly to the night elves, they started speaking mostly in Common.

Trivia

 * The word soustroumpf is a fusion between two French words: sous, meaning "under", and schtroumpf, meaning..."smurf". This is a reference to the smurfs evolving from undertrolls.
 * The use of Soustroumpf explains why the smurfs in the Aeon of the Champion story series have strange-sounding names. The practice was abandoned after relocation to the Smurf Village, where there were only 100 adult male smurfs and so their individuality was more pronounced.