Haven’t memorized the material ? Don’t pretend you have. If you have sides, try to memorize them. But if you can’t, it’s ok. We’d rather hear the material as written with the papers in your hand than hear you make up stuff just to prove that you tried (and failed) to memorize the material (remind me to tell you about the time an actor added a few lines to a Tony Award winning playwright’s monologue to kill time while he tried to get back on track).