My Flat Feet Are ...

... Flatter than the flat earth

... Flatter than a flattop navy ship

... Flatter than a flattop grill in a greasy spoon

... Flatter than the Flatiron building in NYC

... Envious of McDonald's golden arches

... Flatter than a tire that has been spiked

... Flatter than all the flat notes on a piano

... Characters in Flatland

... Caused by congenitally loose ligaments that also gives me double
jointed elbows

... Flatter than my singing

... Flatter than a British apartment

... Flatter than some of these jokes