Appropriate Etiquette For Asking Opponent To Show Heads Up

[Mike_25]

What would be an appropriate way for a player to request that an opponent show his cards face up after all betting is completed? While knowing an opponent's concealed hand could provide valuable insights, one must be careful not to cause offense when making such a request. Kindly share your thoughts on a polite, sportsmanlike way to pose this question to the opposition that would not be perceived as rude or unsporting.