Everyone knows you're not supposed to leave someone else hanging for a high five. It's the epitome of uncool.
But even worse may be accidentally making the gesture for a handshake in front of a dog and having the dog offer its paw for the shake — right as you move your hand away.
The woman in the blue jacket gives the black dog a little ear pet and then opens her palm to the dog, though the gesture was not intended for a handshake. But the dog doesn't know that, poor critter. It's not even an intentional "Too slow!" joke. It gets sadder on every loop.
Obviously, this woman owes the dog an apology, maybe in the form of biscuits or belly rubs.