(noun) one trillion dollars; (descr. noun) the amount the US government is trying to scam from the US taxpayers--Nigerian-spoof style.
Telephone conversation between Bob and Tom:
Bob: "Hey, Tom, I heard those idiot mortgage dudes scammed their companies and left with their pockets full of gigabucks."
Tom:"Yes, they did. And now the taxpayers are going to bail them out to the tune of 999 gigabucks!"
Bob: "Whew. Could be worse, though. One more gigabuck, and we'd be paying a trigabuck. I'm going to have a beer to celebrate how close we came to THAT."
George Bush, listening in to their conversation by wiretap, on the grounds that they could be Nigerian terrorists trying to scam US taxpayers out of a trillion dollars: "Uh, Bob. About that beer--not so fast, there, dude."