tbh, that is called "
Murphy's law" also, or better know as...
Murphy's Law (
'if anything can go wrong, it will.') was first used at Edwards Air Force Base in 1949. It comes from Cpt. Edward A. Murphy, engineer working on Project MX981, a project designed to see how much deceleration a person can stand in a crash. On one day, and after finding that a transducer was wired wrong, Murphy cursed the technician responsible for it and said, "If there is any way to do it wrong, he'll find it". The project manager kept a list of 'laws' and added this one, which he called Murphy's Law.
EDIT:
@may73alliance: edited a bit, cause Sod's law was the original form (but not well known compared to Murphy's law). Sod's law comes from
'it would happen to any sod who needed such a catastrophic the least'. But 'sod' isn't such a nice word and more used (back in the "days") as a flame. Murphy's Law is much nicer and not cursing...
@traxor & Naruto: actually it is "prooven"
What saralk has said is a known fenomena and also you might wanna read:
http://news.bbc.co.uk/1/hi/programmes/breakfast/2311853.stm
And also, did you know that Murphy's law is even used as a "nature" law by scientists in certain experiments? An example (but not the best "scientific" one) would be:
http://ourworld.compuserve.com/homepages/rajm/
In fact. Murphy's law is taken so serious that there are Nobel prices to win when you use Murphy's law in a scientific way:
http://www.improbable.com/ig/ig-top.html
/ 
