Will Poulter had ''a lot of fun'' learning the lyrics to TLC's 'Waterfalls' for 'We're the Millers'.

The 20-year-old actor - who stars alongside Jennifer Aniston, Jason Sudeikis and Emma Roberts in the raunchy comedy - had the unenviable task of reciting Lisa 'Left Eye' Lopes' entire rap verse from the hit 1995 song in one slapstick moment of the film, but says he thoroughly enjoyed preparing for the scene.

Speaking to BANG Showbiz at the UK premiere of the film in London's Leicester Square on Wednesday (14.08.13), he said: ''That was a lot of fun. I actually love rap music and I love TLC so I was very happy to do that.''

Poulter wasn't the only cast member with a tough scene, however, as co-star Aniston - who plays downtrodden stripper Rose in the flick - was challenged with performing a sexy strip, and director Rawson Marshall Thurber thinks she ''nailed it''.

He enthused: ''She had a choreographer named Denise Faye and they did a great job. Jen got in fantastic shape for it and learned the moves really well. She nailed it. It was 100 per cent Jen ... no body double.''

The director was joined on the special blue carpet by the film's stars, Aniston, Sudeikis and Poulter, as well as a host of celebrities including The Saturdays and Joey Essex.

'We're the Millers' is in cinemas on August 23.