I assumed there was a fancy-pants magazine photo shoot in progress and peeked to see who was posing.
Another night, when he started grilling me about other men, I suspected that he had peeked at my cellphone texts.
John peeked out the curtain window, saw me, and immediately opened it and pulled me inside.
late 14c., piken "look quickly and slyly," of unknown origin. The words peek, keek, and peep all were used with more or less the same meaning 14c.-15c.; perhaps the ultimate source was Middle Dutch kieken. Related: Peeked; peeking.
"a peek, glance," 1844, from peek (v.).