The phrase "yea right!" is a common way to express disbelief or skepticism. However, there are plenty of synonyms you can use to convey the same sentiment. Some of these include "yeah, sure," "as if," "I'll believe it when I see it," "you must be joking," "don't make me laugh," "not a chance," "get out of here," and "you're pulling my leg." Depending on the context and the level of disbelief you want to express, any of these phrases can be used to replace "yea right!" and convey your skepticism.