Oxford English Dictionary. Innuendo. 3. An oblique hint, indirect suggestion; an allusive remark concerning a person or thing, esp. one of a depreciatory kind.
Dictionary.com. an indirect intimation about a person or thing, especially of a disparaging or a derogatory nature.
Wikipedia. The term sexual innuendo has acquired a specific meaning, namely that of a risqué double entendre by playing on a possibly sexual interpretation of an otherwise innocent uttering. For example: "We need to go deeper" can be seen as both a request for further inquiry on any given issue or a request to go deeper into an orifice. Alternatively the simple changing of the pronunciation of a word can be used to make it sound vulgar e.g. innuendo to "in-your-endo".