Calendar Confusion
There are twelve months in the year, and remembering which have 30 days and which have 31 can get confusing. That’s where the knuckle trick comes in handy. Start on your left hand at the pinky knuckle and count the months from left to right, with each knuckle and the depressions between them representing one month. January has 31 days.
We don’t know if the July 31st naysayer started by counting January as a 30-day month or if they’ve forgotten the 31st of any month is a thing, but in their reality, George Jetson could never be born. It’s almost as if this person has never seen a calendar or heard of Halloween.