Justin Bieber on drugs?

Pop star Justin Bieber has reportedly posted a video on a social networking site, and he is seen giggling uncontrollably in it, prompting speculation that he may have been on drugs before filming it.

The 15-second video features the 19-year-old shirtless, giggling and laughing uncontrollably while uttering just a few words.

"So, crazy news guys, there is video on Instagram," Bieber is heard as saying in the video, reports dailymail.co.uk.

In reaction to the video, a fan posted: "Justin bieber was stoned in that IG video."

With his black baseball hat worn backwards, a silver chain around his neck, diamond studs in his ears and a tiger tattoo on his arm, Bieber looked like he was fooling around with his buddies in the video.