Justin Bieber narrowly escaped arrest after throwing a water balloon at a US State Trooper.

The singer was about to be cuffed by the officer, who was left fuming after being soaked below the belt by the balloon thrown by Justin, ahead of a sold out performance but the 16-year-old star's bodyguard managed to talk him out of it.

Tweeting about the incident, Justin wrote: "Still laughing. Great Day."

Justin had been working on his aim with the water balloons before scoring the direct hit at the Maryland State Fair last Sunday (05.09.10). He then hid in his trailer while the bodyguard spoke to the trooper, who was at the show for crowd control.

Local news station WBALTV reported Justin was: "Horsing around with members of his staff outside a trailer, when one of the balloons hit a trooper's gun belt and burst, and the other brushed a trooper on the chest but didn't burst."

A spokesperson for the state police described Justin's behaviour as "inappropriate," but confirmed no incident report was filed and no further action will be taken against him or his entourage.

Justin is quickly making a name for himself as a prankster.

He recently panicked fellow pop star Akon by pretending to be his illegitimate son in a phone call.

Akon's manager Scooter explained: "He was like, 'Daddy, why don't you love me?' It really scared the s**t out of Akon!"

When asked about his antics and whether he really makes prank calls by a fan, Justin warned via a twitter post: "R u Kidding of course I do!! I prank everyone!! No 1 is safe :) (sic)"