I'm on a date at the movies and he's being very annoying so I want to walk out.
That doesn't sound fun. How are they being annoying?
He keeps talking during the movie and laughing really loudly.
Sometimes dates don't go as we'd hoped. But it's rude to simply walk out. Think about how you'd feel if someone did that to you.
But I'm trying to watch the movie and don't want to hear him go on about his dogs.
I understand that you're not having a great time, but I don't think you should just walk out without saying anything. I think you should try to stick it out until the end of the movie. Or if you really want to go then you should at least let him know.