There are several synonyms for the phrase "Johnny on the spots." One popular term is "portable toilets" or "porta potties." These are temporary structures that are commonly used in outdoor events, construction sites, and campgrounds. Other synonyms include "outhouses" and "latrines." These terms refer to small structures that are separate from a main building and designed to be used as a restroom. Another synonym is "restroom trailers." These are mobile structures that can be moved to different locations and have multiple stalls, making them ideal for large events or construction sites where there is a need for several restrooms.