twirl one's moustache

verb2

1. •
   To twist the ends of one's moustache hairs around the fingers, especially by way of fidgeting.
2. •
   To express stereotypical villainy in an obvious or comically exaggerated fashion.

   • Picard: Mr. Worf, villains who twirl their moustaches are easy to spot. Those who clothe themselves in good deeds are well-camouflaged. — 1991