In the summer of 2009, 29-year-old Justin Halpern was a struggling comedy writer who’d just been dumped by his girlfriend. So he moved back home with his mother and his sharp-tongued and brutally honest father Sam.

Justin started posting his dad’s quotes for his friends, and one friend suggested he start a Twitter account. In August 2009, Justin started @Sh*tMyDadSays, and within weeks, he had more than 1 million followers.

In a matter of months, he had a book deal and CBS announced it was producing a show based on his tweets starring the legendary William Shatner.

Justin said he thinks his father’s blunt ways have struck a note with people because we’ve become some politically correct in the past 15 years. He says people tell him it’s refreshing to hear a parent tell their kid exactly what they think and not always just give them a pat on the back.

One famous family example occurred on Justin’s first day of kindergarten. After school, he told his parents it was hard.

“It’s kindergarten,” his dad told him. “You thought that was hard? I have bad news about the rest of your life.”

Justin says his father has always been 100 percent honest with him and his siblings. He says in many ways, it really prepared them for the real world where not everyone is there to build you up or tell you you’re doing a good job.

Unlike famous curmudgeons of the past, Justin says his father is a highly educated radiologist who has lectured at Harvard and spent most of his years working in medicine and science.

The 74-year-old Sam Halpern just doesn’t care what other people think, which, Justin says, is why he allowed him to write the book in the first place.

Find out why Justin stuck with the curse word for his New York Times best-selling book, “$#*! My Dad Says” and why he hopes his book changes the way society looks at its elders.