A question so obvious the asker must be an idiot not to know.
Often however, used in a sarcastic tone/context to make the other party look stupid. Making the asker very clever.
Closely related to the Rhetoric question.
Synonyms for stupid question
On this page, you will find 30 slang terms related to stupid question. Some of the top words include: nir, yar buddy, yeah not so much, smupid, huh, and 25 more.