closeted coward

Someone who is secretly a coward, but puts up a brave front until trouble appears.
Doesn't want to admit they are scared of a lot of things. The term goes a bit deeper into their personality than being just a "pussy" or "wuss"

ex:
Jake: Wow! That guy Shane is so cool! He said he'd take on those bullies head on!
Ashley: He says that all the time. He's actually a closeted coward. Once those bullies show up he'll run screaming.