Here's a Halloween make up cut mouth effect as seen on characters like The Joker and it's not difficult to apply.
You don't need glue and there is no latex, they apply in a similar way to tattoo transfers. The result is realistic and flexible. You can add a bit of fake blood to make the appearance complete.
These 3 dimensional transfers give you the appearance of raised flesh cuts. They have been created by Hollywood make up artists but are so easy to use they made them available to everyone. Just follow the straight forward instructions on the packaging. Apply and remove with water.