Connor Conway launched his attack on the man outside the Glasshouse pub, on Bridge Place, at 2.30am, on March 3.
Mary Dixon, mitgating, said: “His ex girlfriend was kicking off with him. He then spotted a man who he believed had been sleeping with her.”
She said the butcher, who lives with his dad, had drunk ten pints of cider and had taken cocaine.
“He says he doesn’t have a problem with alcohol, except when he goes out socially,” she added.
Conway, 23, of Lichfield Close, admitted using threatening words and behaviour, when he appeared at Mansfield Magistrates Court, on Wednesday.
The court heard he received an 18-month community order for assault causing actual bodily harm, in June 2017.
A separate charge of assault by beating was withdrawn because the victim of the attack was unknown, and had not lodged a complaint.
Presiding magistrate Richard Eaton told Conway: “This matter is aggravated significantly by the fact that you used your head - which is classed as a weapon.
“You went back and continued the altercation with the gentleman concerned.”
He said it was “night-time violence” in a town centre, which had been committed while Conway was in drink, and subject to a crown court community order for similar offences.
Conway was handed 12 weeks in prison, and was ordered to pay a £115 government surcharge.