The most common reaction: "What the fu…"
The young guy shown above said that after someone asked him if he was a girl or a boy, he wondered if his face could fool people online. So he decided to put on a little makeup and go on Omegle, a video chat website where random strangers meet, and record people's reactions when he revealed his true gender.
The facial reactions to a male voice coming out of his female-looking face are classic.
The language of most of the deceived is NSFW.
Omegle Prank: Are you a Boy or a Girl?!?