itshigh-boop:

Fact: McCree makes it his life goal and won’t stop until he finds a pet name schmoozy enough to embarrass Sombra to the point where she finally drops that little grin, covers her face and blushes deep. He knows the right one is out there but he hasn’t it found it yet – so he’s just going to keep calling her by the most over the top terms of endearment until he finds it. 

The closest so far is ‘honeysuckle’; she faltered a bit but regained her composure in just a few seconds.