An act of extreme foolishness, superiority or arrogance, performed by someone who is an asshole. This definition is specifically useful in the when alluding to the individual, or, thanks to its propensity for subtlety, in the interest of personal entertainment, as seen in the example below.
"You put the dick in ridickulous."
"My boss just made a completely ridickulous request. It goes to the bottom of the pile."