FUBAR stands for F---ed Up Beyond All Repair.
FUBAR is a military acronym meaning "F**ked Up Beyond All Repair". SNAFU, while also has a real definition, is military slang for "Situation Normal, All F**ked Up".
When Abby calls Gibbs to tell him that the blood on the electric circuit found in the air vent belongs to Lynn Simons, you can see on her computer that she's photoshopping the cowboy picture that Kate uses at the end to counter Tony's blackmail photo. In the end, each of them send their embarrassing photos - Kate winning a wet t-shirt contest and Tony as a shirtless cowboy in leather chaps - to Gibbs.