The phrase "with nothing on" is typically used to describe someone who is without clothing. There are several synonyms that can be used to convey this same idea. For example, one might say that someone is "naked", "unclothed", "bare", or "stripped". Other synonyms might include "au naturel", "in the buff", "bare-assed", or "in the altogether". Regardless of the particular synonym used, the message is clear: the person in question is without clothing. While this kind of language can be considered vulgar by some, it is a necessary component of effective communication and can be used appropriately in certain situations.