HOW THE F**K BLUE IVY GOT A TWITTER ALREADY?

Beyonce and Jay-Z’s baby was trending on Twitter at birth.

The social media site was aflutter Sunday with celebrity pals and relatives of the hip-hop royal couple posting messages of 140 characters or less.

“The most beautiful girl in the world,” Beyoncé’s sis, Solange Knowles, tweeted of her newborn niece, Blue Ivy Carter.

Within hours of entering the world at Lenox Hill Hospital on the upper East Side Saturday night, the infant boasting the lineage of the R&B princess and the rap impresario caused a stir in the Twittersphere.

Some Twitter-geek even set up a phony account for Blue Ivy that drew more than 12,000 followers before it was taken offline.

“I’m blowing up like you thought I would,” stated one of the bogus tweets attributed to baby Blue in the first six hours of her life.

There was no immediate word from the proud parents on the baby’s length and weight.

The legitimate tweets were signed with love and came from a who’s-who list of celebrity friends of the baby’s parents.

As Jay-Z’s protégé and collaborator, Rihanna felt close enough to call the herself the baby’s auntie.

SOURCE