Amanda Bynes tweets pics of her head superimposed onto animals: Who is the most social media-mad celebrity?

Amanda Bynes just keeps getting kookier. In her latest social media aberration, the former Nickelodeon star tweeted pics of her face superimposed onto the bodies of a poodle, a cat and a llama.

But she's not the only one. Earlier this week, Justin Bieber posted a cartoon of himself, topless, embracing a young-looking "Belieber," also topless, to Instagram.

SODAHEAD SLIDESHOW: See the most social media-mad celebrities.

Last month, Miley Cyrus posted a video of herself "twerking" (or dancing) in a unicorn costume. Guess she has a lot of time on her hands...

In this month's issue of Elle UK, Rihanna says: “I’m posting pictures of myself smoking pot to tell the truth about myself." She adds: “Well, I Instagram everything about my life." Clearly!

In 2011, the once Twitter-obsessed Ashton Kutcher apologized for tweeting: "How do you fire Jo Pa? #insult #noclass ... I find it in poor taste." He later recanted with the note: "As of immediately I will stop Tweeting until I find a way to properly manage this feed."

And John Mayer was one of the original oversharers. He quit Twitter in 2010, later admitting that he was a "tweetaholic."

PHOTOS: See the latest celebrity pictures to hit the Internet.

From Amanda to Bieber, let us know: Who is the most social media-mad celeb?