Kesha dropped an expletive-laden birthday message to Britney Spears, who celebrated her 30th on Friday, Dec. 2. Brit was enjoying her big day, lounging in bed with sons Sean Preston and Jayden James as she poured through messages, greetings and well-wishes from fans. Fellow pop starlet Kesha sent Brit a video message, saying "Happy f---ing birthday."

That forced Brit to have to explain the meaning of such profanity to her kids! Brit tweeted:"Thanks Miss Kesha. Just watched this in bed w my boys. Now I have to explain what F---ing means!! U rock Xxoo."

Brit probably did a great job explaining it to her sons.

Zap2It pointed out that Brit was deluged by tweets on her big day, with everyone from Miley Cyrus to Rihanna to Justin Bieber to Katy Perry sending her birthday wishes. And that's just a few of the A-listers who dropped by her Twitter feed to send their love. Brit actually replied to almost every birthday tweet she received. She has such good southern manners!

When her former rival Christina Aguilera tweeted a birthday message, Brit replied: "Thank you girl. Max is so cute! Miss you. Xxoo."

Overall, we've learned that in addition to having to school her sons, Brit is quite the polite tweeter.

Hope your 30th year is your best yet, Brit Brit.