That's easy: here's an equation
Code:
2^((pi*(n+m)/s)
Age = V*-------------------
h+H
where
n = number of pixels in the original Guybrush sprite 1 while idle (from MI 1)
s = number of times Stan moved his arms on all MI games (up to MI 5)
m = number of times Elaine thought about Guybrush
V = Voodoo Lady's constant of unknown, doom and foretelling
h = number of "har" "spoken" by LeChuck
H = number of "har" written on screen in the non talkie versions
You'll have to find the V constant though, by some oddity I have forgotten after asking the Voodoo Lady...