When it comes to synonyms for the phrase "goof around," there are several options to choose from. One such option is "mess around," which implies a sense of playful behavior without any particular agenda in mind. "Lark about," on the other hand, implies a sense of carefree playfulness that can sometimes border on silliness. "Horse around" also suggests a playful demeanor, but with a focus on physical activity or roughhousing. "Joke around" suggests a humorous approach to a situation, while "fool around" can imply a sense of mischievous behavior or even romantic dalliance. Finally, "play around" suggests a sense of experimentation or creative activity, but with a lack of serious intent.