When you rub a dogs or any animals head with affection, A usually casual and mindlessly action, just cause they are there using an open palm or the knuckles of your hand
“Looks like he’s had a rough time of it don’t you fella?” The tea shop keeper gave the dog's head a loving scrubble and Rusty gave a happy yip.
A scrubby-looking attempt at pulling off a short beard.
Michael Che: Have you seen Pete Davidson's scrubble lately? Poor guy....
Lorne Michaels: More like poor "everybody around him."