dab (someone) on the shoulder

Translations
слегка коснуться (кого-то) по плечу
She dabbed him on the shoulder to get his attention.
Она слегка коснулась его по плечу, чтобы привлечь его внимание.
Definitions
To lightly touch or tap someone on the shoulder, often as a way to get their attention or to greet them.