Jack in the Back
A guy who brags about his strength but runs like a chicken when someone dares him to prove it.
He said he'd beat me up, but when I asked him to prove it, he ran out of the room like a scared kid.
She said she'd fight me, but when I approached, she turned and ran.
He bragged about being the toughest, but when I challenged him, he turned and ran like a rat.