The words "who/why/what etc. ever" are often used as fillers in a sentence to express a sense of confusion or disbelief. However, there are several synonyms that can be used in place of these words to add more emphasis or clarity to the sentence. For example, instead of saying "who ever thought this was a good idea?" one could say "who in their right mind thought this was a good idea?" This gives a clearer and more forceful expression of disbelief. Similarly, instead of saying "why did you do that?" one could say "what compelled you to do that?" which adds a stronger sense of urgency and inquiry. Using synonyms can help to improve the impact and effectiveness of a sentence.