Shawn Garan's son Max rarely speaks.

But the father and son's latest exchange left Garan speechless.

Garan, who hails from Stamford, Connecticut, and is in the process of becoming an ordained minister of the United Church of Christ, recently ran an errand with his son.

While in the car, Garan's son - who has autism and "often yells or makes 'mmm' sounds when he tries to respond back" - had a back-and-forth exchange with his dad. Garan asked the questions and Max responded with screams and kicks.

"This was one of those rare times that he stay engaged long enough for me to have a quality back and forth," Garan wrote in the description to the YouTube video of the exchange.

Garan also shared his story on Autism Speaks, an organization that provides information on autism. He said he hopes this video will help people learn to communicate with those who have autism, especially when they have a difficult time speaking.

"I explained to Max that he should try to learn our language because it will make life easier on him. Daily, I challenge Max to push a word or two out," Garan wrote in a blog post for Autism Speaks. "It's actually unbelievable that we've come this far, but here I am, talking with Max, listening to what he might be saying, and doing what I believe all of us should do who are affected. Engage autistic people in the hope that they will engage with you."

About 1 in 68 children has been diagnosed with autism spectrum disorder, according to the Centers for Disease Control and Prevention. It's five times more common among boys than girls, as well.