A 'flats' or humuorous misspelling of 'fats' means that someone is 'fat' but used to escape the wrath of so person.
'Flats' should not be sparingly used as it means no harm.
'Flats' also is used in place for an explicit word.
1. 'Shut up, you flats!'
2. 'Ahh, your such a flats!'
3. 'Shut the flats up!'