A face on a person that shows no emotion, often called poker face because in the game of poker it would be foolish to show any emotional traits that might screw the game for you.

When a reply to a tweet gets more likes than the tweet it was replying to, usually indicating the unpopularity or stupidity of the original tweet

Much like the Guitarface, the Pokerface is used to hide emotion during poker or any other game involving cards.

Most people are incapable of this action as they tend to snicker or jump up and down screaming "FUCK YEA I'M SO GOING TO KICK YOUR ASS WITH THIS 'GET OUT OF JAIL FREE CARD' WHEN IT'S MY TURN AGAIN YOU FUCKING PUSSY!"

Lady Gaga claimed on interview with Jonathan Ross on Friday night with Jonathan Ross. A TV program in the UK that her song 'Poker Face' was inspired by when she used to ''make love'' to her ex boyfriend and she would pretend that he was a girl and that they were having lesbian sex but without telling him, Hence the term 'Poker Face'

an expressionless face(becuase people keep thier faces expressionless during a game of poker)

(in poker) An impassive facial expression cultivated to prevent other players from determining whether one's actions in the game are the result of a quality hand, or of bluffing.
(Lady GaGa's song) similar expression used to prevent giving away one's motives, feelings, or situation. Like in that song when she pretends to like the guy but she's actually thinking about girls.

how to wake up lady gaga
it means: poke her face