Lemme smell your breath
In contrast to humans, who to a great extent use their eyes to see the world, dogs experience the world through their noses. That essentially means why you can’t go for them on a walk without them stopping to sniff each and everything on their walk.
This doggo here observed his opportunity when his friend opened his mouth for a wide yawn and stuck his little nose into his friend’s mouth. The experience on the other dog’s face when he attempted to close his mouth after his yawn makes this snap particularly hilarious!