"Down the tubes" is a common phrase used to describe a situation or outcome that has taken a turn for the worse. However, there are many synonyms for this phrase that can be used to express the same sentiment. Some alternative phrases include "down the drain," "gone to the dogs," "in the toilet," "fallen apart," "gone belly-up," "on the rocks," and "gone sour." Each of these synonyms captures the idea that something has gone wrong and has failed to meet expectations. By using these phrases instead of "down the tubes," writers and speakers can add variety and nuance to their language while still conveying the same message.