"Idiosynchronicity" refers to the phenomena of two or more stupid acts and people being inter-related as part of a larger phenomena or event.
For example, when one of your coworkers pants begin to smoke because of his failure to properly put out the joint he was smoking before he dodged the roach into his cargo pocket, and how that moment coincides with the boss returning from lunch to witness the spectacle, smell the pot, and in his infinite wisdom, check the oven for a burning pizza, not see one, and then pick up the fire extinguisher and go chase through the store looking for it. Meanwhile, your stoned coworker with the burning pants is laughing too hard to notice that he didn't put them out completely, and that they've relit. Now that he's burned, he takes off towards the lavatory, babbling incoherently and managed to scare the boss, who discharges the fire extingisher, thus resulting in 15 innocent people having to take their greasy lunches outside and fend off the pigeons.
As our idiotic ancestors happened to justify the bizarre nature of different people's actions by blaming their variously categorized shortcomings (see also: personality traits) on which ever astral bodies happened to be above the crib at the time of their birth; our modern world recognizes the phenomena of stupidity, but fails to recognize the intricate tapestry stupidity often weaves.