when you wake up in the morning and you stomach is perfectly flat thanks to gravity
and/or you sleeping on it
Friend A: "I hate my stomach!"
Friend B: "Wait it out 'till the morning, you'll feel much better when you look in the mirror"
Friend A: "Yerr, i know, but i wish i had morning stomach all the time."
Friend B: "So does everyone, dude, so does everyone."