A man smuggled a monkey onto his flight by putting it under his hat to go through security and customs!
It appears the man tucked the monkey under his hat when going through customs. The monkey stayed there when the plane took off, but started fidgeting around, so the man took the monkey out and held it in his arms. The monkey was never loose on the plane.
Link - Thanks Tiffany!
See also: Fish Smuggler Caught Because Her Pants Made "Flipping" Noises