An alcoholic walked into a pub with a blade and declared: "I'm going to stab that fat b*****d".
Terry Niblett was armed with a large kitchen knife up his sleeve when he entered the Fox Inn at Hawkesbury Upton.
Bristol Crown Court heard he was successfully disarmed in the gents.
He had previously been abusive to staff at Yate jobcentre and assaulted police when he was arrested.
Niblett, 46, of Birgage Road in Hawkesbury Upton, pleaded guilty to possessing a knife, threatening behaviour and assaulting police in March.
Judge Mark Horton jailed him for nine months.
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He told Niblett: "No-one is unaware that the carrying of knives in a public place is being regarded as an extremely serious offence.
"The reason for that is because weapons are being carried by too many people on far too many occasions for bad reasons.
"The result, day after day and year after year, is that mayhem can be caused where serious injury or death can readily occur."
Nicholas Lee, prosecuting, said Niblett was verbally abusive to staff at Yate jobcentre, calling one woman a "bitch" and threatening to knock her out.
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Just days later he walked into the Fox Inn, armed with a knife, and made the stab threat before going to the toilet.
In the toilet a friend asked him what he had up his sleeve and Niblett admitted it was a blade.
In a struggle that ensued Niblett was disarmed, stormed from the pub and police were called.
Niblett was abusive when officers called at his home, the court heard, and a stun gun was used on him twice as well as PAVA spray.
In the course of the arrest one officer was assaulted.
Chloe Griggs, defending, said: "He suffers from long-term depression and addiction to alcohol.
"At the time he stopped taking anti-depressant medication.
"When he stopped that the drink increased."
