"A person with an eccentric personality that has used shit loads of narcotics over their life, resulting in a swiss cheese brain effect that lends itself easily to OCD and other psychiatric disorders. Though irritating at times, they can be quite entertaining to those around them, like watching a drunk party clown wetting themselves."
This term comes from the fact that average golfers tend so say these 2 words often.
Also a funny joke What is the difference between a bad golfer and a bad sky diver?
A bad golfer goes - whack...fuck!
A bad skydiver goes - Fuck...Whack!