Irish fans were loving Peter O'Mahony's outburst after a reckless clearout from Argentina's Tomas Lavanini on Cian Healy in the international match at the Aviva on Sunday.
Lavanini saw red in the second half after making contact with Healy's head in a bad challenge.
The Argentine flanker has a poor disciplinary record - with this his third red playing for the Pumas.
It was a challenge that Healy was lucky to emerge from without serious injury, but he could count on his captain to have his back.
An irate O'Mahony bawled at Lavanini: "'You knew exactly what you were doing. You think you're a hard man? Watch yourself."
He added sarcastically: "That's very unlike you, isn't it."
O'Mahony was then apologetic to the referee after being told to cool down, but he had already further endeared himself to Irish fans.
The Munster captain was immense for Ireland today as they recorded a 53-7 victory over Argentina at the Aviva.
It was a great end to the year for Andy Farrell's side who saw off Japan, New Zealand and Argentina during the November series.
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