According to a new report from the Sunday Times, William's speech included a "filthy" joke about "wet knickers."
The day after the wedding, a source told E! News that William compared falling in love to a little boy "wetting himself."
"My brother is clearly in love. Being in love is like a little boy wetting himself. You don't know you are doing it, everyone else knows and you get a warm feeling," William reportedly said. "With all this talk of love, everyone is emotional, even the cake is crying."
Another source described William's speech as "naughty" to the Daily Mail.
William and Harry's father, Prince Charles, also reportedly joked about the cost of the party, telling guests, "The budget is out of the window on this one."
Harry's oldest friend Charlie van Straubenzee also mocked Harry's red hair and joked about his "shameless" abuse of teddy bears. A source told Us Weekly he also joked about Harry's tabloid scandals.
Although the wedding night reception at Frogmore House near Windsor Castle only had about 200 guests and no cell phones were allowed, several guests and insiders have leaked details. For example, sources said Serena Williams won a game of beer pong, while Idris Elba was a guest DJ.
The Late Late Show host James Corden reportedly hosted the evening, even getting Harry, William and Charles to take part in a dance competition.
Harry and Markle, now known as the Duke and Duchess of Sussex, made their public debut as a married couple on Tuesday during a Buckingham Palace celebration of Prince Charles' upcoming 70th birthday.
Harry also mentioned the attack during his speech at Buckingham Palace, thanking Emergency Services personnel.
"I would like us to take a moment to remember all those affected by the tragic events at the Manchester Arena a year ago," Harry said. "We are fortunate to have over 250 representatives from the Emergency Services here today. It is right that we take a moment to recognise the amazing work they do every day and how each member of our Blue Light Services rise to meet the challenge of tragic events such as the attack a year ago. We are also joined by Youth United Cadets. Their organisation also provided triage support to the medical crews on the attack."
Charles, who is next in line to the British throne, turns 70 on Nov. 14.