http://www-users.cs.york.ac.uk/~susan/cyc/g/graham.htm
Like something out of Monty Python! R. L. Graham proves that a particular math problem has a solution, and that the solution is less than Graham’s Number—a number so large that a special notation is required to write it down. (According to this page, “if all the material in the universe were turned into pen and ink it would not be enough to write the number down.”) Graham’s Number is an upper bound. What do experts suspect (but can’t prove) the actual solution to be? 6.
(Rad big number notation.)