The phrase "most peed" refers to something that has been urinated on the most. Synonyms for this phrase could include "most marked," "most stained," or "most soiled." Other possible synonyms might include "most fouled," "most contaminated," or "most tainted." These words all suggest a sense of something that has been dirtied or marred by contact with urine. Depending on the context, there may be other words that could also be used to describe the same condition, such as "most wetted," "most saturated," or "most soaked." Ultimately, the choice of synonym will depend on the specific context in which the word is being used.