Anthony Edward Ayres, of no fixed address, appeared before the Isle of Wight Magistrates' Court on Tuesday.
He admitted common assault, and assault by beating, on April 23.
Prosecutor, Ann Smout, told the court Ayres had been a resident at Sandham House at the time of the incident.
She said he threatened a fellow guest while drunk, and approached another with clenched fists.
Mrs Smout said he later punched one victim in the stomach, causing considerable pain.
In police interview, Ayres admitted making threats, and told police he could not recall most of what happened.
He said the assault was "just banter on his part", believing the victim to be his friend, but said he was sorry if he hurt him.