One of the world's biggest pop stars celebrated a personal milestone when she turned 30 on Friday, and the whole Twitter-world was on hand to greet her.

For her birthday, Britney Spears enjoyed a well-deserved break from her South American tour to go ice skating in Houston with long-time beau Jason Trawick. According to Us Weekly, the pair was all smiles as they had some fun on ice, Trawick helping the birthday girl stay upright.

Spears' celebrity pals were among the many to greet the pop diva on her special day, and Spears took care to acknowledge each message.

Reality star Kim Kardashian welcomed Spears "to the 30's club" with a tribute entry on Celebuzz.

" I wish you all the best for this next year and beyond. You're going to love your 30's! I love you and hope you have a magical day," Kardashian writes on her blog.

Victoria Justice's greeting had a holiday twist on it as she says, "I would like 2 [sic] wish the amazing Britney Spears a magical birthday. BTW, "Santa Can U Hear Me" has always been 1 of my fave Christmas songs."

"Happy birthday Britney Spears... 7 years and so many frosted tips later, we're both finally 30!" Ryan Seacrest writes on his Twitter account, taking a dig at himself.

Spears responds in an equally playful manner saying, "Next step for you are extensions!"

Former NSYNC member and long-time friend Lance Bass jokingly calls Spears "grandma" in a tweet, but Spears deflects it with a trip down memory lane.

"You knew me when I was celebrating my 18th! Wow. Feels like yesterday," she writes.

Fellow pop princess Christina Aguilera, supermodel Heidi Klum, Randy Jackson, Paris Hilton and Nicole Richie were among the other celebrities who gave a shout out to the singer on Twitter.

Spears resumed her Femme Fatale tour on Sunday with a free outdoor concert on Mexico City, "with the assistance from the Mexican government."

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