W.K.I.A.A. is an abbreviation for We Knew It All Along. It is used when friends warn/express to other friends what they think is going to happen to their friend and later it does happen to them.
We told you not to go out with him. Told you that W.K.I.A.A. Next time listen to us!
Does he take you out to dinner, the movies, bowling or attempt to do anything that interest you in public? If not then drop him immediately no matter what his excuses are. Don't be a w.k.s. or wks (well kept secret).
W K Y stands for Would Know Ya.
This evolved as an offshoot of the reply D K Y . It began sometime in the 1970's by localteenagers. Basically it was just a fast mouth reply to another insult.