“Paralytic” was how a defendant described his state to police officers after throwing punches at a friend in Westgate.
Wayne Keeton, 48, was seen lunging towards and throwing punches at another man at 3.15pm on August 8.
Daniel Pietryka, prosecuting, said it took three officers to restrain Keeton and pin him to the floor.
However, as the victim did not want to make a complaint, no assault charge was made. Instead Keeton admitted a public order offence.
Keeton, of High Street, Sheringham, Norfolk, was in Grantham for an 18th birthday party and told police officers he was “paralytic” and did not know why he attacked the man.
Chris Pye-Smith, defending, said: “He accepts he drank too much. He has no idea what sparked it off.
“He knows the other male. They are friends.”
Keeton, who works as a cook, was fined £100 and must pay £85 in costs and a £20 surcharge.