The tingly feeling that originates under your balls and moves forward towards your base. This is caused by excitement, nervousness, and being grossed out. Can be shortened to NBT.
Q: Looking at Kevin Ware's broken leg makes my leg hurt.
Me: It gives be a nervous ball tingle, not a good NBT but a "I want to throw up" NBT.
Me: "In waiting for the Athletics Surplus Sale, I get a HUGE NBT. "