Pat (someone or something) on (something or some place) phrasal verb informal
To touch someone or something gently with the hand.
Mark patted the dog on the head when it came obediently.
Shin patted me on my knee and told me everything would be fine.
My father pats me on the shoulder whenever I am sad.
To touch someone or something quickly and lightly in passing
The verb "pat" should be conjugated according to its tense.
It was often said by a photographer when he would like small children to look at the camera and smile before he took a photo.
When the photographer said “watch the birdie”, all of us looked at the camera and smiled.