The phrase "dream on" typically means to dismiss the possibility of something happening or to express disbelief. There are several synonyms that can be used interchangeably with "dream on" to convey a similar sentiment. For example, the phrase "fat chance" can be a substitute, meaning that it is highly unlikely to occur. "Pipe dream" is also a viable alternative, as it denotes an unrealistic or imaginary vision. Other synonyms for "dream on" include "wishful thinking," "not a chance," and "in your dreams." These phrases are often used in a humorous or sarcastic manner to express skepticism or doubt in someone's expectations.