It looks a lot like a snowflake but he revealed yesterday it was in fact a Viking compass.
That makes a lot more sense, because what would a rugged prop be doing with a tattoo from the Frozen movie?
The Viking compass does not have any special significance.
"It just looks cool," he said.
But just maybe it has helped the 22-year-old negotiate a path from the front row of the Southland Stags, through a breakout season for the Highlanders and into an All Blacks jersey.
It has been a meteoric rise for the 122kg front rower, who has been named on the bench for the All Blacks’ test against Fiji at Forsyth Barr Stadium tomorrow night.
It is a dream come true for the quiet Southlander.
"I’m just proud," he said.
"I found out on Tuesday, so I rang my parents.
"My old man is in Australia. But they are just super proud and Mum is coming up."
His Mum will be joined by half of Gore, where de Groot hails from, if the grapevine is to be believed.
"At the start of the year, I had goals just to play five games for the Highlanders and everything has just sort of happened."
De Groot said his parents and First XV coach, Peter Skelt, had been a huge influence on him.
Highlanders and All Black team-mate Aaron Smith had also had a positive impact.
"When I got named, he took me under his wing and sort of showed me the ropes and told me to be myself and grab the opportunities with two hands."
All Black hooker Codie Taylor is looking forward to packing down with his new team-mate.
"From what I’ve seen in Super Rugby, he gets around the park well and he is strong," Taylor said.
