She revealed that she smashed his luxury Audi car when he was away and paid $3,000 to get it repaired without him ever finding out.
Rebecca said: "Do you remember last year, when I took your car in for an early service? Well, I actually smashed the front of your car, reversing in."
"I took it straight to Audi was like 'you need to fix this!'"
But the usually light-hearted funny man was so impressed with his girlfriend of almost five years.
"I've got mixed feelings about that, the lie's bad," he said.
"I didn't lie though! If you had asked 'did you swipe the front of my car on the garage?' Yes, I did. But you didn't ask," Rebecca responded.
Andy replied: "Do I have to ask every night, whether you're sleeping with Steve from next door?"
Last month, the pair holidayed it up in the Balearic Islands, Spain, where fans thought the comedian might have finally dropped to one knee and proposed.
But, alas, it has not happened yet.
The gorgeous pair went public with their relationship in January 2015 after meeting while Bec was waitressing part-time to cover uni costs.