štipati

1. to pinch; to nip
   Prestani da me štipaš, boli! — Stop pinching me, it hurts!
   Baka uvek štipa unuke za obraze. — Grandma always pinches her grandkids' cheeks.
2. (of smoke, cold, onion) to sting; to bite
   Dim me štipa za oči. — The smoke is stinging my eyes.
   Jutros mraz baš štipa za obraze. — The frost is really biting at my cheeks this morning.

The perfective is uštinuti; often used with za + accusative: štipati za obraz.