"That would hang us, ever mother's son."

It's going to happen. It's just inevitable. Somebody is going to forget their lines. Somebody is going to misplace a prop. Somebody is going to enter from the wrong side of the stage. You just have to accept that it's going to happen. But when it does, you'll have to remember to improvise. As they say, the show must go on. If it's the night of the performance, we can't just scream "Cut!! Okay, let's try it again!!" And even more than that, we can't freak out for freeze up. You have to work around it. The show must go on, and you're going to make it go!!

If you're talking with somebody, and they forget their line, you'll quickly notice the awkward pause that rises. If you remember their lines, you may be able to prompt them subtly. Try to remind them of their next line. If their line is "Hey, would you like to drop by a restaurant for lunch?" You could quickly improvise with "Oh, I sure am hungry!!" This will hopefully jog their memory to their next line. If it doesn't you can always try to whisper their line to them quickly and quietly, without attracting too much attention to yourself is possible. If neither of you can remember the line, you can always try to skip ahead to the next line, as long as it fits within the conversation.