Definition of "flattie"

All the rube had to do was throw a baseball into a barrel and get a prize. How hard could that be? But the barrel was rigged with a false bottom as resilient as a trampoline so that a ball thrown from the specified distance invariably bounced out. Not everything was a flattie.

2008, Darryl Wimberley, Kaleidoscope, page 96

Flatties were in use on Pamlico and Albemarle Sounds of North Carolina, employed for shoal water fishing and trapping and usually manned by black boatmen ... no duck-hunting or use of guns was allowed by the local white men.

1982, Frederick Tilp, The Chesapeake Bay of Yore: Mainly about the Rowing and Sailing Craft

This is the "flattie" model of this skiff — there was also a V-bottomed version similar to the m odified sharpie of Figure 6-4.

1993 -, Reuel B. Parker -, The Sharpie Book, page 106

“SOMEDAY,” Hitchcock told me, “there will be three-dimensional wall Video screens, and Dial M for Murder will come into its own. But at the time I was making that picture, I worried that 3-D might be a fad that would fade and that Dial M would go out as a 'flattie.' […]

2008, Charlotte Chandler, It's Only a Movie

A carnival hawker may run a legitimate game in which you have a fair chance to win, but then again he may be a flattie — a carnival grifter expert at separating the unwary from their money.

1997, Josh Wilker, Austin Sarat, Classic Cons and Swindles, page 39