This is based on a quote from Gibbs in Missing when he tells Tony "If you wanna look like a gay pirate, that's your call"
Yo Ho Ho, A Pirate's Life For Tony
"This is the song that never ends," Tony's singing wafted over to Kate across the bullpen. "…it just goes on and on my friends… someone started singing it not knowing what it was, and they'll continue singing it forever just because… this is the song that never ends, it just- "
"DiNozzo!"
"Yes, Katie?"
"Stop. Singing. That. Goddamn. Song."
"I can't Katie, weren't you listening to the words? The song never ends! Listen… This is –"
"Keep singing and my foot will be so far up your ass my shoelaces will be dangling out of your nose."
"Ooo… big words for a little lady!"
The glare Tony received in response was so intense that Tony thought she'd burn his skin with her eyes.
"OK Katie, I won't song that song anymore."
"Thank you," she said through a clenched jaw. Tony then stood up and moved in front of his desk. He then proceeded to bob up and down whilst singing "a sailor went to sea, sea, sea."
Kate silently laid her head on her arm. He didn't stop singing and she could see him doing the actions in the computer screen reflection. Despite her best efforts, she couldn't keep a smile from her face.
Suddenly, Gibbs appeared from nowhere and slapped Tony upside the head.
"I told you DiNozzo, if you wanna look like a gay pirate, that's your call, but save it for after work, got it?"
Tony cleared his throat and sat down. "Got it Boss."