I don't think it's a slang term at all. I mean, let's dissect this. "Upside down." Well, that means that the upper part of your body (basically waist to head) is turned to be below the lower part of the body (waist to feet), or "inverted," which would lead to the term "inversion."
My definition of it is the body going past 90ยบ from directly upright. Thus, Millennium Force's overbanked turns turn you "upside down."
Besides, I said it's my opinion on it. I'm not forcing (no pun intended) my views on anyone. ;)
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How dare you vanquish the Steel Phantom without his consent? Fear the Phantom's Revenge.
*** This post was edited by Lynch on 12/23/2000. ***