"Neato" is an expression from the late fifties to mid-sixties meaning "cool" which is another expression from that era. "Neato" is a variant of "neat," generally meaning nice or extra nice.
"Cool" actually derives from the language of jazz musicians of the fifties and late forties. I am a Miles Davis admirer. One of his best known albums is "The Birth of Cool." Jazz musicians of those times called music or whatever they liked "cool." The expression gained popularity in the larger population outside of the jazz community.
"Whacked" or as is often heard ,"just plain whack," is a more current expression meaning "crazy." "Whack" is probably outmoded now by newer teen jargon. Being from the Jurassic Period (I am 65), the only reason I can keep up is through movies or TV shows directed to mainly younger audiences. Oddly enough, the older I get, the less appealing I find such shows, so I am losing track of the latest slang. In fact, it seems like a waste of time, if the truth be told. For me, it is no longer "cool" to be up on teen slang. In fact, it is just plain whack.
i sure am glad somebody knows what teen slang means cause i sho' nuff dont. everybody that i hang out with is over the age of 40 and we just talk like everybody else in my town does, i am officially uncool because of this but i dont care
War Means Fighting And Fighting Means Killing - N. B. Forrest
When war does come, my advice is to draw the sword and throw away the scabbard." Stonewall Jackson