The mathematical pun here is working on multiple levels. Seven contains the letters "even" despite being an odd number (7). In mathematics, even numbers are divisible by 2 (like 2, 4, 6), while odd numbers aren't. So yes, technically it is odd that "seven" contains "even." Just like how it's suspicious that the word "monosyllabic" has five syllables. Mathematicians secretly love these linguistic paradoxes while pretending to care only about numbers. We keep a collection of them in the department break room next to the expired coffee.