The actor was promoting the new Twilight film Breaking Dawn on Jimmy Kimmel Live! in America when the host asked him if reports about his modelling experience were true.
The flustered pin-up turned to his mum, who was in the audience, and asked her to clear up the story.
Pattinson said, "I was talking to my mum about this earlier... It's one of my little talk show stories that I've used over the years, like, many, many times and now my mum's in the audience and I knew that because she's here, someone's gonna bring it up - and she's like, 'That's completely untrue!'"
But the British star insisted he didn't just make the story up, adding, "I think, like, a lot of my dreams have intermingled with reality now."
He then turned to his mum and asked, "Is this true? Did I ever do hand modelling?"
Pattinson's mother shook her head and mouthed, "Not true".
The red-faced star then said, "I was trying to think of other stories, so I could get out of this... I've done a lot of butt modelling, which you (mum) have no idea about - and you can't refute that... I'm a butt double for, like, a lot of different actors."