That's one of my favorites, here's another:
Why do mathematicians always confuse Halloween and Christmas?
Because 31 Oct = 25 Dec.
For those of you who, like me, had no idea what this joke meant, here's an explanation I found after short google search.
Why do mathematicians always confuse Halloween and Christmas?Because 31 Oct = 25 Dec.The humor lies in the similarity of the abbreviation for October/Octal and December/Decimal, and the coincidence that the two representations equal the same amount (31 Octal is 3*8 + 1 = 25 Decimal).
I'm not groaning, but it does make my head hurt.