J, who was an original member of the nineties boyband, chose not to reunite when 5ive regrouped for The Big Reunion earlier this year, but he's still remained close friends with Abz.
Abz, 34, who came second place on this year's Celebrity Big Brother, had a personal appearance and gig session at Popworld bar and club in York.
His girlfriend Vicky Fallon had teased earlier in the day that a "special guest" would be joining them, and it turns out that person was J!
Vicky was all smiles as she stood in-between the two lads for a quick photo. Posting the snap to Twitter, she said: "A thorn between two roses..."
Abz entertained the crowd with a quick music session on the night, but we don't think J joined him on stage! Vicky later added: "Love this pic of us..Had sooo much fun @PopworldYork..Gotta love an impromptu #RoadTrip."
J kept a low profile following 5ive's inital split back in 2001. When approached to reunite for the ITV2 reality show, all band members including Abz, Ritchie Neville, Scott Robinson and Sean Conlon chose to regroup, except for J.
However, J did make a sensational return for mini-series The Big Reunion: On Tour last month, where he spoke to Abz explaining his reasons for not joining the band, and also hit back at accusations made by fellow bandmates throughout the TV series.
Go back in time and watch 5ive's music video for 'Keep On Movin' below: