The circumference of a circle is two pies times the radius. Only understood the station? That's hardly surprising. After all, jokes are notoriously difficult to translate, especially when it comes to puns. Anyone familiar with the English language knows that in English the word for pie and the pronunciation of the circle number ? are homophones. Based on this fact, you can take the rare opportunity to combine mathematics and linguistics in one joke. The I Ate Some Pie mug even goes one step further and uses other mathematical terms and symbols: The square root of minus 1 alludes to i, 2³ equals 8, sigma denotes a sum and pi, as mentioned above, can be interpreted as a pie. If you put it all together, you get i eight sum pi, which is homophonic to the correct sentence I ate some pie. We have left the addition "and it was delicious" in letters as normal to give non-mathematicians and non-linguists a hint. Now nobody can claim that you can't combine science and the humanities... ;)