Film Called Mad Mask... Help!!!!?

When I was around 10 I'm 27 now a family friend (whom am no longer in touch with) played a film for me and my brother. It was a horror film. The plot was a group of teenagers go to an amusement arcade which consist of a museum and cinema, amongst other things. Befor entering the cinema one of the character (a girl) tries on one of the masks in the Museum. The mask leaves a cut on her face which she doesn't really bother with. She then enters the cinema with a few of her friends and they start watching the film. She goes to the toilet during the film. As she has been away for a long while one of her friends goes into the toilet to look for her. When she opens the toilet booth she sees her friend who has turned into this monster. This then transfers and goes on and on and the cinema becomes manic and everyone runs for their life.

This film was really scary, I've been trying to track it but don't know the title. Please help!!!!!!