Jurgen Klopp was shown a yellow card along with opposite number Antonio Mohamed during Liverpool's Club World Cup victory over Monterrey - leaving social media users bemused after the bizarre altercation.
The German tactician was incensed when Mohamed had appealed for Joe Gomez to receive his second yellow card, and was snapped jokingly repeating the Monterrey manager's gesture.
But followers couldn't help but see the funny side of the spat, with the Reds later scoring a stoppage time winner to reach the final of the showpiece.
The disagreement between both technical areas began in the 76th minute, when centre back Gomez's accidental handball went unpunished with the scores finely poised.
Mohamed could be seen visibly berating the official for not handing the England international his marching orders, and it was the coach's action that had clearly angered Klopp.
Referee Tobar Vargas waved away the appeals from the sideline having already spoken with Gomez, but soon booked both managers after Klopp had sarcastically mimicked the Argentine.
One Twitter user described Klopp's booking 'as crazy', while another said: 'Ref really just booked Klopp... give it a rest!'.
A third added: 'Think their manager was waving his hand to get one of our lot booked - Klopp just told him to behave!'
And it was the former Borussia Dortmund boss' team who emerged victorious in Doha, following Roberto Firmino's last-gasp finish.
Naby Keita had fired the Premier League giants into the lead, before Monterrey hit back when Rogelio Funes Mori swept home from Alisson's parry inside the box.
Liverpool will face Flamengo in the final, after the Brazilian outfit eased past Al-Hilal in the second semi-final.