innocent megan
An innocent Megan is a phony or a fake. The 'Innocent' in front of Megan is completely sarcastic as an 'Innocent Megan' is not really innocent at all. In most cases "Innocent Megan" is a polite way of calling someone a whore.
My old girl friend is such a skank. She's totally an Innocent Megan! I saw her posting ads online to jack off guys for money.