According to The Sun, the Prince and his girlfriend Chelsy Davy stunned pals by vanishing into the toilet for 20 minutes at a nightspot.
And when they emerged they looked "like a pair of naughty schoolkids", a source at a club in Cape Town, South Africa, was quoted as saying.
Harry has been romancing society beauty Chelsy Davy, 19, for eight months.
The Prince had recently invited Chelsy to join him for a week of his stay at the ranch. And he spent most evenings in a cosy guest cottage with the Zimbabwe-born babe.
The couple first met when Chelsy was a sixth-former at posh Cheltenham Ladies' College near Harry's home at Highgrove.
The 20-year-old prince has since visited her in Cape Town, South Africa, where she is a university student.
