Welcome to our weekly Twitter Roundup, where we take the funniest, most popular, wierdest, or most profound celebrity tweets, and put them in one place for you. This week we have Bieber on tour, Lambert bashing bullies,  Rihanna undressing for the camera and more.

Biebs is on his way to Nashville - and his fans can't wait. 15K+ RTs

Nashville is next

— Justin Bieber (@justinbieber) January 17, 2013

Shakira, Gerard Pique and soon-to-be-born child use their popularity to support UNICEF. 5K+ RTs

We'd like to celebrate the imminent birth of our first child with all of you. #babyshoweruni.cf/baby Shak twitter.com/shakira/status…

— Shakira (@shakira) January 16, 2013

Steve Martin being...Steve Martin. 800+ RTs

My chimney just got a flue shot. #withapologies

— Steve Martin (@SteveMartinToGo) January 15, 2013

Justin Timberlake celebrates newest single's hit success. 3K+ RTs

So humbled by all of this. This day has been TOO crazy. I just have to say it one more time to all of you guys and gals... THANK YOU!!

— Justin Timberlake(@jtimberlake) January 15, 2013

Anthony Bourdain suffers through a crappy flight. 400+ RTs

Latest news is it took #AA two hours to admit a passenger dropped a wet deuce on a seat. Need to change planes

— Anthony Bourdain (@Bourdain) January 15, 2013

Rihanna shows she's 'complex' 1.5K+ RTs

#complex instagr.am/p/UewHQJBM5z/

— Rihanna (@rihanna) January 14, 2013

LiLo pulls a Twitter Kanye. 400+ RTs

why wasn't Snow Patrol nominated with their song, "Lightening Strike" for Act Of Valor? - I LOVE Adele! She is AMAZING!but, just curious?

— Lindsay Lohan (@lindsaylohan) January 14, 2013

And finally, Adam Lambert puts his foot down on bullying. 600+ RTs

it's a case by case thing. If someone's being so viciously bullied that its affecting their mental health - yes- huge problem we must stop

— Adam Lambert (@adamlambert) January 11, 2013

That's it this week folks! Check back next Friday for next week's Twitter Round Up