For those interested, there is a community up called: ncis_headslap
Also, this least contains more than just head slaps. I only started with episode five, The Curse, because it was the first one that had a head slap. Let me know if I missed something you think should be listed. I'll get it added with all the details.
Total Head Slaps: 6
Receiving Head Slaps
Giving Head Slaps
01x05 The Curse
32:31 Gibbs slaps DiNozzo
Reason: DiNozzo joked throughout the case about Gibbs’ eyesight and age. The last straw was DiNozzo saying, “Don’t strain your eyes, Boss.” Also of note, at the start of the episode, it was the day before DiNozzo’s 2-year mark at NCIS and being on Gibbs’ team. “That’s kind of touching Gibbs, remembering the day you hired me.” To which Gibbs responded, “Yeah. Well, seemed like a good idea at the time.”
01x08 Minimum Security
04:59 Gibbs slaps DiNozzo’s hand
Reason: DiNozzo bumped into Gibbs at the elevator spilling the coffee. DiNozzo tries to brush the coffee off of Gibbs’ suit and Gibbs slaps his hand away.
01x10 Left for Dead
33:24 Gibbs slaps DiNozzo
Reason: DiNozzo was not telling Gibbs what he wanted to hear and instead was talking about needing some time with the blond secretary of the German bomb-sniffing firm. Gibbs: “What’d you pick up? Anything?”
DiNozzo: “Well, give me a few minutes with this girl and—“
18:21 DiNozzo slaps McGee
Reason: DiNozzo is working the scene with McGee who is temp fill in. This is the first time DiNozzo slaps McGee and also the first time someone other than DiNozzo is slapped.
McGee: “You enjoy this, don’t you?”
DiNozzo: “Having fun at your expense?”
McGee: “Yeah.” DiNozzo: “Really a lot.” *slap*
23:58 Gibbs slaps DiNozzo
Reason: Gibbs, DiNozzo and Kate are discussing the case and Kate is working with the theory that Gibbs first proposed that the suspect is innocent.
Kate: “We think Curtin is innocent, right?”
Kate: “Assume he’s innocent for the sake of argument.”
Gibbs: “Because I said to.”
DiNozzo: “Innocent. Sure. Why not.”
Gibbs: “Go on.”
Kate: “If Curtin’s innocent and he’s going after the guy that murdered his wife and the cable repair man-“
DiNozzo: “I don’t think he cares about the cable repair man.”
Gibbs: *slaps DiNozzo*
31:40 Gibbs pats Ducky’s cheek
Reason: Ducky discovered that the cause of death originally reported in the case was wrong and that the victims had their heads snapped prior to the cuts on the throat. Gibbs patted Ducky’s cheek with a smile.
01x19 Dead Man Talking
19:22 DiNozzo brushes something off of Gibbs’ shoulder
Gibbs: “Is your apartment still for rent?” (while Tony brushes his shoulder off)
Man: “You guys-- together?”
Gibbs and DiNozzo smile at each other and DiNozzo laughs.
DiNozzo: “No. It’s not what you’re thinking.”
15:17 Gibbs throws DiNozzo’s cup out the car window
Reason: Gibbs, DiNozzo and Kate are in a car in rush hour and DiNozzo annoys Gibbs.
DiNozzo: “Rush hour. Kind of a misnomer if you ask me.”
Gibbs: “I didn’t.”
DiNozzo: “I mean it’s not like anybody’s really rushing anywhere and it always takes more than an hour. They should call it like--"
Gibbs: “Shut up and sit there before I shoot you out.”
DiNozzo: “I was thinking of something a little shorter.”
DiNozzo slurps his drink.
Gibbs grabs the cup and throws it out the window.
DiNozzo: “That’s littering.”
Gibbs: “Fine me.”
43:28 Gibbs places hands on DiNozzo’s cheeks
Reason: They got DiNozzo back safely after he was kidnapped.
DiNozzo: “Admit it. You were worried about me. Right? You don’t have to say anything. I know. Okay. I want you to say it. You care, right?”
*they walk out of the elevator*
DiNozzo: “So, you saying you don’t care?
*they stop and Gibbs turns around to face him*
Gibbs: “Tony, as far as I’m concerned,” Gibbs placed his hands on DiNozzo’s cheeks, “you’re irreplaceable.”
DiNozzo: *smile* “I knew it. I knew behind the whole Marine thing you’re really are, at heart--"
Gibbs: “Forget about it McGee, he’s still alive.”
01x21 Split Decision
07:10 Gibbs slaps DiNozzo
Reason: McGee is installing software to check Ari’s picture against yearkbook photos from Britain universities. DiNozzo joked about Ari, which Gibbs didn’t take too well due to his fixation on the man.
DiNozzo: “Who said our terrorist was British?”
Gibbs: “Ducky. He thought his syntax suggested higher education in the British Isles.”
DiNozzo: “Oh. Maybe he just grew up watching tons of Cary Grant movies.”
07:46 Gibbs tousled McGee’s hair
Reason: McGee finished adding the software to sear for Ari.
Gibbs: “That’s great work McGee.” *tousle hair*
McGee: “Any time Boss.”
DiNozzo: (to Kate) “Look at that. He gets a pat on the back and I get a smack on the head.”
Kate: “Aww. It doesn’t seem fair, does it?”
Kate: “But it is.”
18:33 Kate slaps DiNozzo
Reason: Kate, DiNozzo and Ducky are eating lunch and DiNozzo takes the lemon from Kate’s drink and dunks it in her drink.
DiNozzo: (with a full mouth) “Maybe he’ll take his frustrations out on a mysterious redhead instead of us.”
Kate: “Must you talk with your mouth full?”
Kate: “So who was Gibbs chasing when he divorced his last wife?”
DiNozzo: (as he reaches in Kate’s glass) “Had to be a redhead.”
Kate: (slaps DiNozzo)
DiNozzo: (shocked face) “You’re not Gibbs. You do that again, you’re gonna be wearing that tuna salad.