You're born
An alternative saying to "happy birthday", particularly over text/social media, typically reserved to people who are close friends / family and have dropped all formalities, instead aiming for a blunt, dry humor that signals lack of care for one's birthday but is actually the opposite.
Facebook: "Daniel's birthday is today, send him a message!"
Nick: "You're born."
Daniel: "I am birth."
Nick: "You're born."
Daniel: "I am birth."