There are some things you just don't do, and annoying a man with a rifle, especially if he's a member of the Queen's Guard, turns out to be one of them.

This tourist learned that fact the hard way:

The video posted June 22 shows a tourist at Windsor Castle, outside of London, marching alongside the guard before daring to place his hand on the soldier's shoulder. Almost instantly, the Queen's Guard shouts "Step back from the Queen's Guard!"

A spokesperson for the Ministry of Defense told the Daily Record that the soldier had an "appropriate reaction" to the tourist's behavior and would not be disciplined, according to The Telegraph.

Mocking, posing and walking alongside, generally trying to be a nuisance to the famously stoic - and silent - members of the Queen's Guard is something of a sport among some tourists to the royal residences, according to the Guardian.

"Since that incident, a rope has now been installed at that sentry position that keeps tourists away and stops people from approaching the guard," the spokesman said.

He added: "It is disappointing that a member of the public has shown such disrespect towards the Queen's Guard. The Queen's Guard is under orders to protect Her Majesty, The Palace and his post," reported the London Evening Standard.

Future tourists pay attention: don't mess with the Queen's Guard.