The expensive lesson you didn't see coming

[Alan]

A buddy of mine accidentally left his tractor key in the 'on' position all night. It drained the battery, and the charger he tried to use to bring it back to life didn't work either.

What forgetful moment has cost you some cash?

 

[casesensitive]

I once forgot to put the fuel cap back on and rainwater got in. As a result I had to shell out for a complete system flush.