Two friends were riding along on a tandem bicycle when, suddenly, the one at the front slammed on the brakes, hopped off and began letting air out of the tyres.

“Hey!” the one at the back said. “What are you doing that for?!”

“My seat was too high. I wanted to lower it a bit,” the first guy replied.

The one on the back then jumped off in frustration, loosened his own seat and spun it around to face the other direction.

“Now what are you doing?” the first guy asked his friend.

“Look, mate,” the back rider said, “If you’re going to do stupid stuff like that, I’m going home!”