The phrase "idiot brother" is used to describe someone who is not very smart or makes silly, foolish choices. It is usually said by someone who is frustrated or annoyed with that person's behavior. Full definition
Yeah, and somebody was also saying that in Idiot Brother, of my three sisters, two of them I have played opposite in other movies where we were either married or romantically involved. (film.avclub.com)
Commented TWC Co-Chairman Harvey Weinstein, «We'd like to dedicate our new red band trailer for OUR IDIOT BROTHER to censorship everywhere. (mediamikes.com)
Jack Quaid (son of Dennis and Meg Ryan) and Brian Gleeson (son of Brendan and brother of Domhnall) play Joe Bang's idiot brothers who are introduced as they're tossing toilet seats like horseshoes, and somehow they work, but Hillary Swank as a late - in - the - game FBI agent with a bizarrely controlled cadance is a misfire. (decider.com)