A man who drunkenly turned up to a beer garden revving a chainsaw displayed "lunatic behaviour", a judge said.
Mark Jones, 39, of London Road South, Lowestoft, pleaded guilty to affray after an incident on 10 December.
Ipswich Crown Court heard he had returned to the Kings Head pub in Beccles 15 minutes after he was asked to leave, "roaring the chainsaw".
In mitigation, Jones's lawyer said his actions were "foolhardy to the point of reckless".
The court heard Jones had threatened door staff he was going to come back with the power tool when he was asked to leave.
Police had been called and were at the scene when he returned 15 minutes later.
Jones got no closer than five yards to the pub, it was heard.
Sentencing Jones to a 21-month suspended jail sentence, Judge David Goodin said it was "lunatic behaviour".
He said: "The thought of a big man, which you are, drunk at a pub with a chainsaw roaring, is almost unimaginably frightening.
"The temptation to send you straight to prison is almost but not quite overwhelming."
Mitigating, Jones's lawyer Stephen Dyble said: "There was not a great deal of thought.
"It must've been an alarming experience to witness but there was no suggestion it was being brandished and it was not being thrust towards anybody."
Jones was also given a curfew between 22:00 and 06:00 seven days a week.