[EricH]

For those saying that W=Fd is wrong, "d" is often used for distance. You could also use "l" for "length", but "d" is more common.

I kind of like the following:

Stress = F/A.
Stress = Homework/Time.
Therefore, Homework is a force.

Oh, and then there's this one:

Reading + Manual + Updates + Q&A = someone who knows the rules and doesn't have to ask [current most annoyingly common rules question].