The phrase "fling on" is typically used to refer to quickly putting on clothing, such as a coat or sweater. There are several synonyms for this phrase that can be used interchangeably, depending on the context. These include "slip on," "throw on," "don hastily," and "toss over." Other options might include "hurry into" or "pull over," as well as more casual alternatives like "pop on" or "throw over." Regardless of the specific phrasing used, the underlying meaning remains the same - to quickly and effortlessly don a piece of clothing in order to stay warm or comfortable.