12,500 showers, one spider

Yet our decision making is based on the single shot of one spider's presentation, not on the rest of 12,499 spider-free experience. Something we all do on daily basis (details from Freakonomics).

Irrational as it sounds, one can argue this seemingly randomness could due to human frailty in knowledge, as Nassim Nicholas Taleb argued in his new book, The Black Swan.