Using an electronic timer
Well, yesterday I decided to have an easy meal - Pizza - and instead of just ordering one, I bought one to cook myself - a lot cheaper...
It said on the package to cook at 210 deg Celsius for 10-12 minutes... I set the timer for 10, and continued to read on MR... I thought a long time had passed, but the timer said more than 9 minutes left...
Then I smelled burned food! This couldn't be right... only seconds had passed! Got the pizza out of the oven - it was black alright.
I blamed the stupid timer, until I realised I had set it for 10 hours and not 10 minutes... Geeze!