Not something you see everyday.
Sgt Jon Harris was encouraged to join in with the Karaoke night, taking place at the Argyle Street pub - moments after a 23-year-old man was arrested for an alleged assault.
Peter McKenna - Boyd, who took the video said: 'Karaoke encouraged him as a joke and he done it, now even Gloria Gaynor retweeted it. It's mental. I wasn't expecting this at all.'