Labrador syndrome
When someone loses focus like a dog that just got distracted by a squirrel and forgets why they were running in the first place.
I was about to finish my test when I saw a video of a dancing cat and started laughing like a lunatic.
She was in the middle of a big argument when she saw a bird and forgot everything.
He was about to propose to his girlfriend when his dog ran in and started barking at the neighbor's cat.