A man shopped himself to police when he became angry in a town centre while armed with a knife, Lincoln Crown Court was told.
Scott Cooper telephoned officers telephone police to say that he was in Gainsborough Market Place and wanted to hurt someone.
Edna Leonard, prosecuting, told the court: “The defendant said that he was in possession of a knife and he was angry.
“Officers went to the Market Place in Gainsborough and he was found sitting on a bench.
“When he saw the police he ran off but was detained shortly afterwards.
“He was searched. He had a Stanley knife in the rear pocket of his tracksuit bottoms and he was arrested.”
Cooper, 23, of Trinity View, Gainsborough, admitted possession of a bladed article in a public place as a result of the incident on March 8, 2017.
He also admitted breach of a suspended jail sentence imposed for harassment.
Judge Simon Hirst jailed Cooper for 15 months.
The judge told him: “Your previous record is dreadful. The only sentence I can impose is an immediate custodial sentence.”
David Eager, in mitigation, said Cooper was a potential danger to himself.
“In this instance he phoned the police himself.
“He is a young man with grave problems.
“He is an insulin-dependant diabetic who doesn’t take his medication.”