Credit: Chris Brown's Instagram.

Chris Brown's back on Twitter and tweeting about - you guessed it - Rihanna.

Less than a week after leaving Twitter following a profanity-laced spat with comedian Jenny Johnson, Brown revived his account Sunday, posting a black and white Instagram pic of himself with a cigarette and Rihanna lounging in the background in her skivvies and a camouflage blanket. He offered this caption: "What would music today sound like if these kids didn't exist?"

This morning, the tweet and photo were no longer on Brown's Twitter timeline.

PHOTOS: Chris Brown and Rihanna Heat Up

He and Rihanna have been spending a lot of time on Twitter and Instagram over the past few weeks. Last Thursday, Rihanna posted a photo of her kissing Brown's head on Instagram, her body wrapped around his. "I don't wanna leave!!! Killed it tonight baby!!!" she wrote, likely referring to Brown's concert that night in Frankfurt, Germany.

The two celebrated Thanksgiving in Berlin and shared a variety of semi-clothed snapshots of each other over the holiday weekend. Rihanna tweeted a shirtless photo of Brown, followed by her own topless photo.

Despite all the steamy pics, they're not confirming that they're back together. In an interview with Power 106 radio host Big Boy last month, Brown said he and Rihanna are "working on their friendship."

He elaborated, although not eloquently: "As far as our personal life, I think people just got to give it a chance - or not even give it a chance, but shut the hell up. It's me. At the end of the day, whatever opinion they have ain't going to change nothing I'm doing."

Rihanna's adopted a similar attitude. She brushed off the "obsession" about her and Brown in a recent interview with Vogue, saying "The world hasn't let go. They haven't seen any progress in our friendship, because they don't see anything."

Rihanna and Brown split in 2009 following his brutal assault on her.

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