The word "wacks" is a slang term used informally to describe something that is either nonsensical or crazy. However, there is no single synonym for this word as its meaning can shift depending on the context of the sentence. Some words that can be used interchangeably depending on the situation includes bizarre, weird, odd, insane, nonsensical, irrational, and wacky. These words are often used to express the same sentiments as "wacks" and are useful in enhancing communication. It is advisable to use the appropriate synonym based on the context of the sentence to achieve the desired effect.