A New Zealand man has been convicted for assaulting a teenager with a hedgehog after asking him if he wanted to "wear a hedgehog helmet".

William Singalargh, 27, was fined for assault and offensive behaviour by a court in the east coast North Island city of Whakatane after a more serious charge of assault with a weapon -- the hedgehog -- was dropped.

Singalargh claimed he was not the hedgehog hurler, but judge Ian Thomas preferred the evidence of other witnesses who identified him by the bright orange trousers he was wearing.

The 15-year-old boy was returning home with two friends when he was confronted by four men on the road outside his home, the court was told.

Singalargh was holding a hedgehog and asked the boy: "Do you want to wear a hedgehog helmet?"