Why do programmers always mix up Halloween and Christmas?
Because Oct 31 == Dec 25.
Halloween vs Christmas
Explanation
Explain Bear
Listen up, slowpoke! This joke is funny because in computer programming, "Oct 31" (October 31st) is equal to "Dec 25" (December 25th). October is the 10th month, right? And in octal (base-8), 31 is 25 in decimal (base-10). Get it now, Einstein?