The Queen roared with laughter as she met a royal fan who had her cypher inked on his leg.
Camilla, 78, joked with Phil Smith, 61, as he showed her his four large tattoos on his left leg, starting with Queen Elizabeth II's royal cypher and including both Charles and Camilla's individual ones.
His latest - situated on the top of his thigh - is of their joint royal cypher and took about an hour and a half to do.
The two met at the annual Sandringham Flower Show on Wednesday, where the King and Queen toured the exhibition tents viewing winners in flower arranging, vegetable produce and baking.
After showing the Queen his latest inking, Phil said: "She finds it hilarious."
He added: "That was probably about an hour and a half (to ink), but it was b***** painful. I've been corresponding with the Queen since before they got married [in 2005] – we hit it off."
Camilla also revealed that one of her personal protection officers also has a royal cypher tattoo.
"She pulled up her police officer's sleeve and said, 'Look, it's catching on!’" Phil said.
The King and Queen received a warm welcome from hundreds of guests at the show, with many shouting goodwill messages for Charles, who is receiving ongoing cancer care and who missed last year's event.
Maria and Graham Sharples from Spalding, Lincolnshire, who regularly visit the show, called out to the King saying: "We missed you last year, you look very well."
Mrs Sharples said: "He came over and said, 'It's all done with mirrors'."
Royals with tattoos
The King's niece, Princess Eugenie, 35, has a small circle inked behind her ear, although the royal has never revealed the meaning behind it.
Within the Swedish monarchy, Princess Sofia, 40, – the wife of Prince Carl Philip – has a tattoo of a sun between her shoulder blades, as well as a butterfly inking on her rib cage and a small one on her ankle.
King Frederik of Denmark, 57, has a shark tattoo on his lower right leg, as well and an inking on his upper right arm, referencing his nickname Pingu from his time in the Danish Frogman Corps.