A Texas grandfather has been labelled the “coolest papa out there” on social media after photos of his impressive flag pole lift on a train in Rio de Janeiro were shared by his grandson on Twitter.

Wayne McEntire, 68, was riding on a train with his grandson, Britton Barker, when a commuter offered him a seat in a designated section for elderly passengers.

But Mr Barker’s grandfather respectfully declined, instead walking a few steps down the carriage and demonstrating his upper body strength with a flag pole lift.

Mr McEntire’s spontaneous display has since gone viral after it was shared on Twitter by his grandson, who had his camera ready filming his ride back from the Olympic Games.

@b_flex14 Why isn’t he in the Olympics competing? #ForTheGold #Rio2016

— Kathy (@ltlmscantbwrong) August 12, 2016

“Oops accidentally made Papa Twitter famous,” Mr Barker tweeted after seeing the online reaction to his grandfather’s public display.

Mr Barker told the ABC he did not expect the response it had received.

“I was pleasantly surprised at 5:00am when I got woken up by the buzzing from all of the notifications and I realised it had gone viral,” he said.

The original tweet has received more than 66,000 retweets and drawn a number of responses online.

“My new life goal is to be like your grandpa. How do I make this happen?”, one user asked.

“Hands down coolest Papa out there,” another said.

Mr Barker said his grandfather performed tricks like that all the time.

“While I didn’t know exactly what he was doing, I knew it was sure to put a smile on my face,” he said.

This is Mr McEntire’s fifth Olympics, after first visiting the 1984 LA Games with his daughter and wife.

He also attended the 2000 Sydney Olympic Games to watch his good friend Brandon Slay take the gold for the US in wrestling.