Perhaps the zebra on the left had bad breath. Perhaps he told a bad joke. Whatever the case, the zebra on the right was clearly not having any of it. This shot was taken during the short rains in Kenya, when the males are busy fighting for dominance and mating rights.
Nikon D300 with Nikkor 200-400mm (at 290mm) ISO 400, f/6.3 at 1/800th of a second