treptati

1. to blink
   Gledao me je i nije treptao. — He was looking at me without blinking.
   Dete je pospano treptalo. — The child was blinking sleepily.
2. (of light) to flicker; to twinkle; to flash
   Lampica na ruteru stalno trepće. — The light on the router keeps blinking.
   Na nebu su treptale zvezde. — Stars were twinkling in the sky.

The perfective is trepnuti, often in ne trepnuvši 'without batting an eye'.