Best definition
Someone that is crazy

You know what I think about Susan, I think she is a whack-a-do
whack-a-do: define #2
A whackado is a person who is ‘out there’, whacked in the head in a retarded, crazy and psycho way.
A guy says to his friend: “One time, I tried to break up with this girl. She just didn’t get it! Went into a deluded frenzy, cutting up my clothes. Then, two seconds later, she’s asking me what I want to eat for lunch! “

Friend responds: “Man… What a whackado!”

Guy : “No… whack-a-do!”