Tom Cruise's toughest crowd during 'Rock of Ages' filming

WireImage

Tom Cruise had to impress a tough crowd during "Rock of Ages" filming.

Tom Cruise didnt want to embarrass himself.

The blockbuster star has done lots of things in front of the camera couch-jumping, dancing in his skivvies, stare-downs with Jack Nicholson but he hadnt been known for his singing talents before signing on to star in the film adaptation of Rock of Ages, which hits theaters June 15.

To prepare for his role as Stacee Jaxx, Cruise took singing lessons and added a shaggy wig, tattoos and black nail polish.

He was all ready to perform Def Leppards Pour Some Sugar on Me, he explained in a Friday visit to Tonight Show with Jay Leno. And then the day before filming, he found out that the English rockers would be stopping by to listen.

Im just trying to honor you, Cruise told Def Leppard before singing their iconic song.

We played the whole song, and most of the crew was watching (Def Leppard) for their reaction, Cruise told Leno. The bands lead singer (Joe Elliott), walks over and points at me, and I cant say what he said some sort of obscenity, and they had us perform it again for them. They were very generous.

Tom C! ruise as Stacee Jaxx in "Rock of Ages."