Prince William and Prince Harry were joined by their wives, Kate Middleton and Meghan Markle, to celebrate the 100th anniversary of the Royal Air Force on Tuesday in London. The fab four arrived in style at Westminster Abbey and later took up on the Buckingham Palace balcony to watch the military fly-past. While there, it appeared that Will, Kate, and Meghan shared a laugh at something Harry wasn't in on; the 33-year-old newlywed looked a little confused as the trio cracked up. It reminded us a bit of when Harry was Kate and Will's third-wheeling pal before Meghan joined the show!