A man making his way home after a night out was attacked as he stopped at a Rishton cash machine to get money to pay for his taxi.
Blackburn magistrates heard the victim cancelled his transaction to allow Lee Benson to go before him.
But even after the gesture Benson, who admitted to having drunk about 18 pints of beer and several vodka shots, punched the other man to the floor and then kicked in the head.
Benson, 29, of Gladstone Close, Blackburn was convicted after trial of assaulting Ryan Chambers causing him actual bodily harm.
He was sentenced to six months in prison suspended for two years and made subject to community supervision for two years with a condition he attends the Addressing Substance Related Offending programme.
He was also made subject to a weekend curfew for three months and ordered to pay £600 compensation and £600 costs.
Philippa White, prosecuting, said Mr Chambers was using the cash machine when Benson and another man approached.
"They appeared angry and told him to hurry up," said Mrs White. "To avoid any confrontation Mr Chambers cancelled his transaction and moved away, allowing Benson to use the machine before him."
Mr Chambers returned to the machine and made his withdrawal but was immediately approached by Benson who became abusive and without warning punched him in the face.
Mr Chambers suffered a black eye and a cut inside his mouth which required nine stitches.
Police were able to trace Benson by checking bank records which showed he had made the withdrawal immediately before Mr Chambers.
Basharat Ditta, defending, said his client accepted the circumstances would cause the magistrates concern but urged them to suspend any prison sentence.