Shithouse is a colorful aphorism for an outhouse, or a commode not connected to another structure. The word has been immortalized in the phrase "brick shithouse", as in "built like a brick shithouse". The term is an appreciative nod to overengineering, and frequently applied to the female body. Only a man could be so crude as to favorably compare a person to an outhouse.
This term is also frequently used to indicate the portable chemical toilets commonly known as porta-potties.
It is sometimes used in the same sense as doghouse: in the shithouse can be used similarly to in the doghouse.