Years and years ago on the B737 flight (multistops) between Vancouver and Whitehorse one of the Captains had his own entertainment.
Once at cruise he would turn the aircraft over to the first officer, and then tie two strings to the back of his seat. He would then back out of the cockpit holding one string in each hand. The copilot would watch the tension on the strings and when the right one was tightened he would bank right. When the left was tight he would bank left (etc.) (Of course nobody in the cabin would see any of this)
The captain would then get as far as the first row of seats and ask one of the passengers sitting there if they would mind holding onto the strings while he went to the loo. He would explain that the copilot had called in sick that morning and he had to fly solo. He really needed the loo and would the passenger oblige by holding the strings tied to the wheel. Most often the pax would agree and the captain would disappear into the lavatory. The copilot would then initiate a series of slow banks causing the passenger to pull on the opposite string. After a few minutes of this the Captain would come out of the loo, take the strings back, say thank you, and return to the cockpit. Nothing further was said but the cabin erupted in laughter.
I saw this myself a couple of times on that otherwise very boring flight, and many of the regulars knew the game as well.
Impossible today though
