A young man was overheard saying he would "love to rob this place" while he and an accomplice were drinking in a bookmakers.
Sean Hoey (21) was on a "cocktail of medication and alcohol", according to his solicitor, who said he had no intention of carrying out the threats.
Judge Victor Blake fined Hoey €450 and imposed a two-month sentence suspended for 12 months.
Hoey, of Dublin Street, Balbriggan, admitted before Swords District Court to public drunkenness and threatening and abusive behaviour.
Gda Colin Noonan said he received a call about a panic alarm at Boylesports in Balbriggan last November 19 and encountered Hoey walking down the street.
He and another youth had been in the bookmakers and Hoey had made a number of threats to staff.
Hoey, who had been drinking, was overheard to say: "I'd love to rob this place."
Gda Noonan said there was one female member of staff in the bookmakers at the time.
Defence solicitor Fiona D'Arcy said Hoey suffers from acute transient psychosis, is not capable of taking care of himself and his mother is his full-time carer.
She stressed that Hoey had no intention of carrying out the threats he made.
Judge Blake told Hoey he should get his mother "a nice present for Easter".