Okay, I got a few samples from Northshore for their Supreme Briefs, small and mediums.
I've yet to try out the mediums, but let me tell you about the smalls....
I feel like I'm wearing a baby diaper, they are that small.
My waist is around 28-29" I'm also 6'4" tall.
Their website states smalls are 22" to 32" I fall in the upper scale of them.
I fit, however they are quite snug, mainly the leg openings. The top is about 2.5" below my belly button.
So if you're looking for a diaper that is similar to a baby diaper size, these might interest you.