12/03/2011 at 06:00 AM EST
While Britney Spears
was celebrating her 30th Friday by ice-skating in Houston with boyfriend Jason Trawick
, her celebrity friends were sending her birthday messages or homemade videos.
"Happy birthday to the beautiful Miss Britney Spears! Welcome to the 30's club, Brit!!" Kim Kardashian
told the pop star 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."
and Justin Bieber
phoned Spears on Friday, while Nicki Minaj and Lance Bass (who kiddingly called his old pal "grandma") – not to mention hundreds of her biggest fans – posted videos to honor her. Rihanna
, Katy Perry
(who wrote, " Happy B-day, Brit Brit!"), Ke$ha, Pauly D, Heidi Klum
, Miley Cyrus
and others sent their well-wishes, as did Ryan Seacrest
: "7 years and so many frosted tips later, we're both finally 30!" he wrote
, while also posting an old photo
of himself with Spears. Her response: "Next step for you are extensions!"
The pop star enjoyed reading many of the messages and watching the videos while in bed on her big day with her sons Preston, 6, and Jayden, 5. She also thanked many of her friends and fans on Twitter
"Thank you girl. Max is so cute! Miss you. Xxoo," Spears responded to Christina Aguilera
. Bass also got a special note: "You knew me when I was celebrating my 18th! Wow. Feels like yesterday," Spears
The birthday girl resumes her South American tour Saturday and plays a free show in Mexico City on Sunday before closing out her world tour next weekend.
Additional reporting by PERNILLA CEDENHEIM