He's world-class and he's from Carlow.
For years that sentence was reserved for Richie Kavanagh.
That was until a force of nature emerged from Tullow Community School, headed to Dublin 4 and started to knock heads.
The epitome of success for the club rugby system, O'Brien is also as Irish as complaining about The Late Late Show on Twitter or laments about any and all types of weather.
Here are 18 definitive signs that Sean O'Brien is the most Irish of Irish sportspeople.
1. He doesn't take praise too well
After being praised for his excellent outing against the All Blacks, in Dublin, O'Brien exhaled and looked none too impressed. He replied:
"I think I'm a little bit off still. I think I've a lot of improvement in myself in different areas.
"That's why I'm looking forward to this week, to build again on last week and see where we go from here."
That's the sprit Sean.
2. Massey, yer only man
You said it, sure.
https://www.instagram.com/p/BKyP6wDAO4c/?taken-by=seanobrien678
2. He never forgets his roots
https://twitter.com/SeanOBrien1987/status/685040050619461632
4. He's mad for ripping the piss
5. He doesn't take kindly to accusations of puking in bins
https://twitter.com/paddyb_ireland/status/656446441125228544?ref_src=twsrc%5Etfw
https://twitter.com/SportsJOEdotie/status/656580421652774912
6. Off-season! What off-season?
https://twitter.com/FightingCocksIE/status/473587127448788992
Imagine peeking out of the dressing room to see that you were marking this guy in your Junior B match?
7. He bloody LOVES The Ploughing Championship
On a rest day during last year's Rugby World Cup, O'Brien and Rory Best paid a visit to a 'grass management farm'.
Yes, a grass management farm. They literally spent their day off watching grass grow.
"We’re just going to have a look around it," he beamed.
You don't get that with Manu Tuilagi.
8. His Twitter cover photo is a joy to behold
9. He has put his body on the line for his country, and paid the price
From Stephen Ferris'
Man and Ball:
10. He likes horsing people out of it
11. Pre-season training away from GPS trackers and computer print-outs
https://twitter.com/SeanOBrien1987/status/482205583542878208
12. Honesty is Sean's only policy
On the toll injuries will eventually take on his body:
13. Wheelbarrow surfing. He's a fan
14. He's not the greatest fan of soccer
"I absolutely hate soccer," he declared during the 2011 World Cup.
"I never really have liked soccer, to be honest. I played a bit when I was younger but I wouldn’t be a big fan of watching it now. I think they get paid way too much money for what they do, and they’re jumping and rolling around half the time."
15. Seanie's no averse to sharing post-match beers with the Irish fans
16. He's never too far from a pair of wellies
https://twitter.com/SeanOBrien1987/status/672459346849226752
17. Even the greatest Irish player of all time is in awe
From Brian O'Driscoll's
The Test:
18. Did we mention that he has never forgotten his roots?
http://twitter.com/SeanOBrien1987/status/331832803190796288
He's Irish and he's proud...
https://www.instagram.com/p/BGPuS8EHp4x/?taken-by=seanobrien678
