Unfortunately for Pro Green, it seems that Millie doesn't take well to being made a fool of on national radio.
The rapper was taking part in 'Call or Delete', a game devised by Nick Grimshaw which sees a celebrity having to prank someone in their phone book or risk having their number erased.
With girlfriend Millie Mackintosh being the target of the prank, Pro rang her up to confess that he had been papped holding Imogen Thomas's hand.
Bad idea Pro. Very bad idea.
[Related story: Professor Green has a Millie-related Twitter rant]
[Related article: Professor Green and Millie Mackintosh forced to separate?]
He told Millie: "When I was coming out I bumped into something and got papped. I bumped into Imogen Thomas."
An unhappy Millie responded: "Why would you even talk to her. You just got papped talking to her?"
The Pro Pranker then told Millie that they had bumped into each other at a coffee shop with the Made in Chelsea star responding: "You got papped having coffee with Imogen Thomas? I can imagine the headlines already."
Professor Green then pushed his luck saying: "I'm so sorry. It looks like we are holding hands too. But we weren't, it was completely innocent."
Raising her voice, a shocked Millie told her boyfriend: "Why would you be holding her hands. Stephen, are you joking? You wouldn't go for coffee with Imogen Thomas in your right mind."
Once all was made clear to Millie Mackintosh that she had fallen foul of a prank in the name of entertainment, the reality star took to Twitter to air her thoughts on the joke.
She tweeted: "Let's just say someone isn't getting any.... For a while."
We'd start groveling now if we were you Professor Green.