The phrase "mucking about" is commonly used to describe an activity or behavior that is aimless, silly, or unproductive. There are a variety of synonyms that can be used to convey a similar meaning, including "fooling around," "messing around," "playing around," and "wasting time." Other alternatives include "lollygagging," "dilly-dallying," "idling," and "lounging." Some more informal options might include "chilling out," "hanging out," and "lazing about." Regardless of the specific term used, these words all convey a sense of casual, unstructured activity that is generally devoid of purpose or direction.