Prime Minister Justin Trudeau's toast to Queen Elizabeth at the Commonwealth leaders' summit dinner in Malta on Friday elicited a rather cheeky response from the Queen.

During the toast, Trudeau reminded the Queen he was the 12th Canadian prime minister to serve during her reign and that his father, Pierre Trudeau, was the fourth.

Then it was the 89-year-old Queen's turn to speak, and a Royal Family Twitter account summed up her response succinctly.

That prompted a tweet from Trudeau's own account declaring the Queen "forever young."

"One of the things both my father and mother taught me about the Queen is that she has a wonderful sense of humour and last night she was very gracious," Trudeau told reporters on Saturday.

Here's the full text of Trudeau's toast to the Queen:

"Ladies and gentlemen,

"As the Commonwealth's newest head of government, I am honoured to offer toast to Your Majesty, Head of the Commonwealth and Queen of Canada. In so doing, I am deeply mindful of Your Majesty's long and tireless service to the Commonwealth and its citizens.

"As Head of the Commonwealth you embody our family of nations and the values expressed in the Charter collectively endorsed three years ago. Your example of dedication and selfless service inspires as we strive to build our societies on the principles of respect, inclusiveness and dignity.

Justin Trudeau speech Queen Elizabeth toast malta Commonwealth Nov 27 2015

Prime Minister Justin Trudeau delivers his toast in honour of Queen Elizabeth before a gala dinner during the Commonwealth leaders summit in Malta on Friday evening. (Alessandra Tarantino/Associated Press)

"You were only nine years old when you carried out what was perhaps your first official duty on behalf of Canada — an appearance on a postage stamp. That was 1935. From that moment to this, Your Majesty has been such a constant presence in the life of Canada that a modern history of our nation could be written entirely with vignettes from your life.

"Here's one: In 1951, Princess Elizabeth attends her first hockey game, in Montreal, at the legendary Montreal Forum. And another: in 1959, Queen Elizabeth opens the St. Lawrence Seaway. And another: In 1967, Queen Elizabeth cuts Canada's centennial cake on Parliament Hill as Canadians sing Happy Birthday.

"There are countless scenes like these to choose from. In a single tour in 1959, over 45 days, you visited 90 towns and cities. It is safe to say that you have seen more of Canada than almost any Canadian. And always, Canadians have watched and admired their indefatigable queen, forming cherished memories.

"Some of those memories are of formal state occasions. Some are more personal. And for a few, some are both.

"One that I personally remember well from my childhood and indeed, treasure is this: It is 1982, again on Parliament Hill. Queen Elizabeth signs the Constitution Act, thus empowering Canada's legal foundation, including our Charter of Rights and Freedoms.

"On that cool day in April, seated next to you, was my father. Pierre Elliott Trudeau was your fourth Canadian prime minister. I am your twelfth.

"In 1947, you famously vowed that your whole life would be devoted to the service of the Commonwealth. You more than honoured your vow. And for that, on behalf of all Canadians and indeed, of all of us citizens of the Commonwealth, I thank you.

"I now ask you to rise, charge your glasses and join me in a toast to Her Majesty the Queen. The Queen!"

Then it was the Queen's turn to speak.

Here's what she said, according to the British Monarchy's website.

"As Head of the Commonwealth, it is with great pleasure that I welcome you all here this evening.

"Thank you, Mr. Prime Minister of Canada, for making me feel so old!

"We are grateful to be with you for the second Commonwealth Heads of Government Meeting hosted by Malta, and I hope that this occasion will allow you to gather as friends and enjoy Malta's hospitality."