Two friends from Leven in Fife appeared together at Perth Sheriff Court after T in the Park.
Thomas MacNeil, 18, of Chemiss Road, walked into court while Stuart Wallace, 22, of Rosemount Grove, appeared from the cells.
Wallace pleaded not guilty to two charges of threatening and abusive behaviour and lashing out at officers by struggling violently and wrestling them to the ground.
MacNeil pleaded guilty to assault by throwing a can of beer at officers.
Sentencing him, Sheriff Lindsay Foulis told the teenager he was “stupid” for getting involved in the fray, which has put a “blemish” on his record.
The sheriff fined MacNeil £300, which he must pay at £10 per week.
Meanwhile, Wallace was bailed until his trial on December 2.
Appearing separately, Callum Campbell, 30, of Cresswell Street, Liverpool, was charged with possession of ecstasy and being involved in the supply of cocaine during T in the Park.
He pleaded not guilty and a trial date was set for December 3.
