Prince William revealed sailors tampered with his hip flask when he attended the Submariners' Remembrance Service and Parade on Sunday.
The Duke of Cambridge was joined by hundreds of current and former submariners at the a wreath laying ceremony in central London.
During the ceremony, the submariners drank a toast from hip flasks to "absent friends".
When asked if he had brought his own hip flask at a reception afterwards, William said: "I'll never be asked twice about drinking, it's very important.
"They tried to put a Jägerbomb in there. Imagine my surprise - burnt my throat!"
He recounted the story again later, saying: "They tried to put Jägerbomb instead of rum - that would have sorted me out was expecting rum and got a Jägerbomb."
Earlier during the ceremony the duke laid a wreath for those who died manning submarines and the Royal Mariners Band played the national anthem and hymns.
Among those present at the ceremony in Middle Temple was Jim Booth, a 97-year-old D-Day veteran who survived an attack at his home last year.
Chaplain to the Submariners Association the Reverend Paul Jupp, who led the ceremony, urged those in attendance not to forget the sacrifice made by submariners.
He said: "History and remembrance are merged by the coming together of us old shipmates and those who are actually doing the job now - a job that we were so proud to be part of in days gone by.
"A few of us will remember the submarines that were lost and a few of us will remember people who served on them.
"May all of us make a real effort to learn the story of their service and to carry them on into the future."
A roll call of lost submarines was read out while the wreaths were laid.
Gillian Molyneux, whose husband was killed on board HMS Astute in Southampton in 2011, laid a wreath on behalf of the submariners' widows.
The ceremony this year had added poignancy because of it being 100 years since the end of the First World War, she said.
"I think remembrance is not just about remembering those who lost their lives, but also remembering those who are still serving," she added.
"It is definitely a time to say thank you."
William, who is the Commodore-in-Chief of the Submarine Service, then met with submariners in Middle Temple Hall for a reception.
The annual ceremony, which is held every year a week before Remembrance Sunday, was first held in 1923 after the National Submarine Memorial was unveiled on the nearby Victoria Embankment in 1922.
Additional reporting by Press Association
