From Longman Dictionary of Contemporary Englishsteal a kisssteal a kissKISSto kiss someone quickly when they are not expecting it → steal
Examples from the Corpus
steal a kiss• As a matter o' fact we sat on this very seat, an' if I remember rightly, I stole a kiss.• She was a beauty and he'd often wanted to steal a kiss, but had had enough sense not to try.• He embraced her in bars without any embarrassment and stole kisses in shop doorways, no matter who was passing by. 