Packed down
When people mess up the phrase 'down pat' so bad it sounds like they're getting packed into a coffin. Means you've drilled something until it's perfect and you'll probably scream it at someone.
I packed down my multiplication tables so hard I could recite them in my sleep and my brother's nightmares.
My mom packed down the recipe for lasagna so well, she could make it blindfolded and in a hurricane.
The kid packed down his lines so much, he could recite them while juggling flaming torches.