This mathematical proof (and similar variants) can be found all over the internet. The original author is unknown.

And, for the record, this does not apply to my lovely wife.

All boys know that getting girls takes time and money:

girls = time * money

Businessmen say that time is money:

time = money

so:

girls = money^2;

Philosophers say that money is the root of all evil:

money = sqrt(evil)

so:

girls = (sqrt(evil))^2

Simplifying:

girls = evil

QED