What happens next in this paragraph?

How to keep a straight face
Take a deep breath.
It's impossible to laugh while you're inhaling. If you're afraid you can't keep a straight face, take a deep breath in and let it out slowly.
Repeat this as many times as you need to until you feel like you don't need to laugh anymore. Don't take a huge deep breath with your mouth open-it might be obvious what you're trying to do.