Bruce Willis has poked fun at Kristen Stewart and Robert Pattinson's relationship.

The 'Die Hard: With a Vengeance' actor mocked the 'Twilight' stars - whose romance was thrown into turmoil last month when the brunette beauty publically confirmed she cheated on Robert with married director Rupert Sanders - during a sketch on the 'Late Show with David Letterman' yesterday (30.08.12).

Bruce jokingly broke down in tears as he attempted to deliver his catchphrase ''Yippee-ki-yay, motherf***er!'' during a spoof trailer for fake film 'Twi-Hard: With a Vengeance', which shows his alter-ego failing to compose himself, due to Robert and Kristen's broken relationship, while negotiating with a villain.

He cries: ''I'm a little distracted lately, I lost some friends ... Kristen and Rob, Bella and Edward - they broke up! They were supposed to be together forever, goddamnit!''

While introducing the sketch, Bruce managed another dig at the pair by joking that the spoof trailer is a ''pretty emotional scene''.

He told David: ''It's a pretty emotional scene, but very tough. There's a lot of action going on.''

Will Ferrell also mocked the couple's relationship recently and the comedy actor referred to Kristen as a ''trampire''.

Robert has put the Los Angeles home where's he's lived with Kristen for nearly a year on the market for $6.3 million, but the pair are thought to be edging closer to meeting face-to-face in an attempt to patch up their three-year relationship.