Repeat teen offender given eight-month sentence after threatening security worker 

The teen also took part in a vicious mugging  along Dublin's Grand Canal. 

The youth already had 25 prior convictions.

A repeat teen offender has been given an eight-month sentence after he threatened a shop security worker at knife-point.

The youth had also taken part in a vicious mugging along Dublin's Grand Canal and was later caught driving a stolen Porsche car.