Rubber pants are commonly known as waterproof underpants or plastic pants. These pants are designed to keep infants and toddlers dry from any accidental leaks or spills that may occur during potty training. Another term for rubber pants is diaper covers, as they are usually placed over cloth or disposable diapers to help prevent any leaks onto clothing. Other synonyms for rubber pants include waterproof underwear, incontinence briefs or pants, and bedwetting pants. Regardless of what term is used, the shape and purpose remain the same - to provide a waterproof barrier that helps protect clothing and bedding.