;D I used to boil water for tea.  It took a looooong time until i noticed that i forgot to light up the gas   ::)

I watched the vid from this guys. http://www.aopa.org/
Some sort of seminar. One topic was radio setup, and the guy said that very often pilots forgetting to check jacks, volumes both on headphones and radio itself, or trying to "fix" no sound problem with jack plugging - unplugging while the problem is - volume on headphones :)