The 33-year-old - like Richards - is a product of the City academy having joined the club aged nine in 1999.
After loan spells at Barnsley and Burnley, he left the Etihad Stadium on a permanent deal to join the Clarets in 2012.
Trippier failed to make a senior appearance for City, as he joked that he left because he couldn't get in front on Richards.
He eventually joined Tottenham, where he helped them reach the 2019 Champions League final, before moving to Atletico Madrid and winning the LaLiga title there.
Now at Newcastle, Trippier has been part of a squad that survived relegation to finishing fourth last season to gain entry back into Europe's premier club competition.
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Speaking to CBS Sports pitchside ahead of the club's showdown against Paris Saint-Germain, Richards commented on how they were both in City's academy.
To which Trippier quipped: "I didn't make it because of you!"
It drew laughter from the panel, with host Kate Abdo and fellow CBS pundits Jamie Carragher and Peter Schmeichel in tears.
Trippier then joked: "I had to leave! I had to leave!"
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Getting back to his original question, Richards asked Trippier how good it feels to be playing Champions League football with Newcastle after leaving City to join Burnley.
The 43-cap England international remarked: "It feels great, I wouldn't change anything in my career.
"As players, we've all had setbacks, it's all about how you bounce back from them, I've had plenty in my career, I've faced a lot of challenges.
"And it's about believing in yourself and that's all I've done throughout my whole career.
"So when I arrived here, it's all about believing, I never thought we'd be in this position so soon.
"But I think we've earned the right, especially last season to be here now, and it's about showing everybody what we can do as a team."
Trippier started what proved to be a famous night for Newcastle as they sealed a 4-1 win over the French giants.
Miguel Almron ad Dan Burn put them 2-0 up at half time before Sean Longstaff put them three up.
Lucas Hernandez gave the visitors a potential route back but Fabian Schar's stoppage-time pile-driver restored the Magpies three-goal lead.