I hate when people clap in movie theaters
Why do you hate it when people do that ?
I thought it was a nice movie, but then everyone stood up and started that annoying applause.
I agree with you on that.  It's super annoying when people make noise during a movie in a theatre.  If you want to clap, do it when the movie is over!
I was so frustrated I felt like going outside and yell.
i understand your frustration. It's very rude to make any noise let alone clapping in a movie theatre. People should have some civic sense.