'Tis the season ... for ugly Christmas sweaters!

Once an endearing gift from a well-meaning grandma, hideous jumpers have become a fad, spawning booming businesses, Facebook groups and sweater parties. 

Savannah picked out some especially gnarly knits for our anchors and a few guests (Brian Williams and Matt Damon got roped in, as well as our crew and the entire control room). Check out the pics below and vote in our poll: Whose sweater is the ugliest?

Upload your own photos of ugly Christmas sweaters. TODAY.com posted some of the worst offenders. 

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Ann Curry, the most influential tweeter of 2010, threw down the gauntlet this morning. She challenged Brian Williams, her co-host for the day, to take the leap and finally start using Twitter!

As you all know, Ann is something of a Twitteratti. She has more than 1.1 million followers and tweets up a storm. Follow her here. Brian, who's launching NBC News' "Rock Center" Monday at 10 p.m., has dipped his toe into the Twitter water. He signed up for an account months ago -- but hasn't sent a single tweet to his more than 55,000 followers.

We think he needs a bit of encouragement. Tell us exactly what you think would happen #IfBrianTweets.

We’ll be keeping tabs on just how many of you join the conversation (and will retweet some of the best ones on our @todayshow account)!

Brian, who also anchors "Nightly News" hasn’t made any promises, but we think with your help we can get him to take the first step.

What do you think will happen #IfBrianTweets? Let us know on Twitter or in the comments below.

Update at 8:30 a.m.: We've received hundreds of responses in the last 30 minutes. Here are some of the really amusing ones so far.

With the help of what we assume were several loud alarm clocks, Brian Williams joined TODAY this morning to co-host with Ann Curry.

"I actually think Lauer is in the plaza just having a good laugh," Brian said. "Just seeing if Williams would show up for work."

Never fear! Brian arrived just in time this morning, if not seeming a wee bit tired after slow-jamming the news on Jimmy Fallon's show last night.

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To help perk him up, Ann gave the "Nightly News" anchor a massive cup of coffee.

Watch the amusing clip above.

And make sure to catch NBC's new primetime news magazine "Rock Center with Brian Williams" airing Monday night at 10 p.m.

Read about the last time Brian co-hosted TODAY, that time joining Matt Lauer.

Fresh off his news-making interview with President Obama, Brian Williams joined Matt in studio 1A — and got a "tad close" for Matt's comfort. 

During a conversation with Atlanta's 11Alive team of Karyn Greer and Ted Hall, Brian rolled his chair up right next to his buddy Matt. "A little invasion of personal space," Matt joked. 

How did Brian react to the encounter? "What a handsome man up close you are," Brian said. "It's amazing."

Watch the video above and judge for yourself — did Brian invade Matt's personal space? Tell us in the comments. 

And check out more of Brian Williams' amusing appearances on TODAY. 

Ann Curry stars with NBC’s Brian Williams and "Sesame Street's" Big Bird in a new public service announcement to help launch Sprout's “Kindness Counts” campaign.

Check it out in the video below. 

It's not the first PSA that Ann has starred in. She also was featured in one of the clips from The More You Know's campaign.

You can also read about Ann's other charitable acts in our ongoing series, TODAY Gives Back.

On the morning of Ann Curry's first day as co-anchor of TODAY, thoughts and tweets of congratulations, encouragement and welcome came pouring in from TODAY viewers, Ann's colleagues to celebrities like Sting.

But the one that touched everyone the most was from Ann's husband, Brian Ross, and their daughter, McKenzie. Ross cheers his wife on, saying: ”Show ‘em what a Curry can do!”

Watch their touching video below and see others congratulate Ann on her first day.

Share your congrats or warm welcome for Ann in the comments below.

10 reasons we (and you) love Ann

TODAY staff and viewers tweet why they love Ann

On her first day as anchor, Ann feels 'like Cinderella'

Though it wasn't easy, our TODAY anchors braved the snow that blanketed the Northeast this morning and made the commute into the studio.

But some of our friends in Washington, D.C., weren't so lucky, including NBC News' Andrea Mitchell and "Meet the Press" host David Gregory. Watch the video below to hear of their plight.

"Nightly News" anchor Brian Williams barely escaped their fate. He called into The Weather Channel and told their anchors he “had the good sense” to flee the nation’s capital. But was Williams being a bit overly dramatic? Let us know in the comments below.