Buzz Bites (3/23/11): Christina Aguilera Joins Twitter!

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+ "Brace yourselves," Christina Aguilera warned the internet yesterday in her first tweet from her new Twitter account. Follow the singer at @TheRealXtina. (ONTD)

+ Trouble in "S&M" land? Rihanna may have to cancel upcoming tour dates due to low ticket sales. (Buzznet)

+ Hours after his outburst at "Good Morning America" yesterday, Chris Brown was all smiles while visiting a New York art gallery. More of this, Chris. (TheFABlife)

+ The Foo Fighters will hit the "Saturday Night Live" stage for their seventh time next month. Actress Helen Mirren will host. Puh-leeze let them do a skit together. (MTV News)

+ Adorbz alert -- Selena Gomez & The Scene announced 2011 summer tour dates. The Disney cutie and her band will play 25 shows around the country, beginning in July. (Neon Limelight)