There wasn't a single person in the team who had not received or given, one of those.
It was, of course, a tradition which began with Gibbs, but it didn't stop with him.
Every agent was soon using it when talking to another who was saying something stupid and soon it became a little prank most played on each other.
The most usual recipient, however, was definitely Tony, and it was Gibbs who was delivering the blow to the back of his head.
Today was certainly no exception.
Tony was, as usual, boasting about something of the other, and Gibbs was just trying to have a cup of coffee quietly.
Tony was rambling on an on about this movie he'd seen and comparing it to others in the genre, earning himself an eye roll from Ziva.
"Do you ever shut up?" She asked, giving her coworker an irritated and amused grin.
As Tony refused to take the hint, Gibbs finally decided he had had enough.
Walking up to his subordinate from the back, he slapped him across the back of his head, prompting Tony to turn around and open his arms in confusion.
"What did I do now?" Tony asked, though his smile seemed to imply he very much knew what he had been doing to irritate his boss.
"10 minutes of silence in the morning, DiNozzo, that's all I ask" Gibbs replied, prompting Ziva to chuckle rightly,
leaving a finally quiet Tony behind as she stepped away to grab herself a glass of Berry Mango Madness.