Hubby Undermining My Homeschooling Efforts

From the next room my son calls:

"Mama? What is the name of Thor's hammer?"
"Thor's hammer?"
"Yes. Papa said it is "Whack a mole", but I don't think that's right.
"Sigh. Mjollnir. Not Whack-a-mole."
(Husband calls from next room) "I knew it was mole-something."

Anyone know how to say "Papa is an idiot" in Old Norse?