If you are scientifically minded, you know that National Mole Day was created in honor of Avogadro's Number (6.02 x 1023) - a chemistry unit of measure. And if you visit Fayetteville Christian School's Science page on National Mole Day, you'll find a handy list of ways to celebrate.
If you are zoologically minded, National Mole Day probably makes you think of something along the lines of this little guy:
And if you're a comically-minded movie goer (like me), you can't think of or hear or read the word "mole" in any context whatsoever without thinking of the moley scene from Austin Powers in Goldmember. (Note to parents: this is a clean - and funny - clip the kiddos can see):