ORIGINAL: Dirt2
It's hilarious that after 3 pages no one has mentioned the obvious.
IT'S ILLEGAL!
Okay, go ahead and read up on Wyoming game regs, but I can tell you it's illegal in Montana. You may use a decoy only in bow seasons, not in rifle season. I'll bet it's the same in Wyoming.
Sorry,you're probably going to lose that bet. It isn't illegal in Wyoming as far as I can tell.
It isn't mentioned anywhere in their regulations, the only reference I could find was on a FAQ section.
ASK THE GAME & FISH
8/10/2007
Q. "Is it OK to construct a permanent blind and use a decoy to hunt antelope during the archery season?
A. There certainly are no restrictions to using a blind or decoys to hunt antelope, or for that matter, any other big game species. If you're hunting on public lands it is permissible to construct a temporary blind, but the structure must removed after the season. Any construction of blinds on private land is between the hunter and the landowner.
-WGFD-
In the question they mention archery season but in the answer they simply say there are no restrictions. Not a smoking gun either way.