Why 5?

I may be a jerk Off, but what brain this Jerk Off hasn't wasted is always making lists in my head.  And I always make my lists in a top 5 format.  Why 5?  Because 5 narrows it down to the best of the best, the Mount Rushmore (I realize there are 4 presidents on Mount Rushmore, but hopefully you catch my drift) of whatever I am debating.