Justin Trudeau joined Mr Johnson when the British Prime Minister suggested taking off his shirt and revealing his pecs “to show we are stronger than Putin”.
As the sun shone at Schloss Elmau in the Bavarian Alps, where the leaders of the G7 met, Johnson wondered if they should keep their jackets on.
Mr Trudeau chimed in, referring to a “bare-chested ride” – Mr Putin was pictured on a horse in 2009 without a shirt.
Mr Johnson then said, “We need to show our pecs.”
It came as the prime minister insisted that his “golden rule” is to “focus on what we are doing” after revealing he plans to remain in office into the 2030s.
He admitted he’s had “no time” to reflect on the biggest regret of his premiership to date, but claimed the government’s achievements were “remarkable”.
It comes as pressure on the Conservative Party leader from across the political divide has increased after the Tories’ stabbing defeats at Wakefield and Tiverton and Honiton.
During a trip to Rwanda this weekend, Johnson said he is “actively thinking” about fighting the next two general elections to become the longest-serving post-war leader.
Asked at the G7 summit in Germany on Sunday whether his ambitions are delusional, Mr Johnson said: “What I am saying is this is a government that continues to deliver for the people of this country and we all have a huge amount of money. “
He said the “golden rule” is to “focus on what we do” – to tackle the cost of living, the “huge” plan for a stronger economy, and “ensure the UK remains the kind of leadership offer that there is. the world that I know our people want”.