Actually, it's funnyyyyy !!! I hope the same for you Mr History ! =p

She was making a joke by using the literal meaning of history. You said, "I'm history" meaning "I'm leaving" She, jokingly, decided to take "I'm history" to mean that you are a topic of study about the past, of which many books have been written and are available in any library.

The arithmetic /mean/ of A and B, where A and B are numbers is: (A+B)/2. The geometric mean (of non-negative values) is Square-root(A times B). The arith. mean of N values is their sum divided by N. Generalizations to infinite sums are possible under some convergence conditions. C.F. Gauss discovered remarkable properties in the generalized Arithmetic-Geometric-Mean (AGM) linking the expression to the evergreen Greek-Pi.

Your girlfriend is taking the piss out of you and your bad English.

If only Julius Caesar had a bunch of cell phones and maybe an Internet connection, even a low speed one! How History would have been different, a unique and magnificent language would be shared among Terrestrials. == Tony, you are not the only one to wish about History, you see ... Did I answer your question ?