Vole fighting
From Memory Alpha, the free Star Trek reference.
Vole fighting is the act of pitting at least two Cardassian voles against each other for entertainment purposes. Initiating or sponsoring such activity is considered a crime in Bajoran space, including Deep Space 9.
Quark often attempted to secretly stage vole fights in his bar. On one occasion he, along with Morn, were caught by Odo painting numbers on the backs of several voles in preparation for a fight. Though Quark claimed that he was merely "counting them", he was arrested. (DS9: "Through the Looking Glass")
