A teenager punched his victim in the face because he thought he was spreading rumours about him.
The 17-year-old told police he carried out the attack because the other teenager was talking about him behind his back.
The assault happened in Old Heath, Colchester, last November, and the victim, also aged 17, suffered a cut lip.
His attacker, who cannot be named for legal reasons, admitted assault at Harwich youth court.
James Baird-Murray, mitigating, said: "It is the sort of thing that has happened over and over again in the past. Every time youngsters get to the age of 15, 16 or 17, that's when these sort of things happen.
"No amount of law is going to stop it happening. It is just a question of making sure it doesn't continue beyond that sort of age."
The Colchester youth was ordered to do 16 hours at an attendance centre. He must also pay £100 compensation and £60 costs.
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