That's where a mailman valiantly tries to insert the day's correspondence. And where the cat who lives there will dice his ass if he tries to slip one more piece of mail into that slot.
Judging by the video, which was posted to YouTube back in 2014, it's an age-old struggle - one that the mailman has waged again and again in his ongoing mission to deliver the goods.
It starts off ominously as the delivery man approaches the doorstep.
"Kitty cat ready to do battle," the man says.