be talking out of your arse
be talking out of (one's) arse
vulgar slang To exaggerate one's achievements or knowledge of some subject; to bluff or boast. Primarily heard in UK. Dorothy keeps saying she can outrun anyone in our school, but she's talking out of her arse if you ask me. It seemed like the candidate was talking out of his arse for a while when the debate turned to the topic of tax policy and law.
be talking out of your arseBRITISH, INFORMAL, VERY RUDE
If someone is talking out of their arse, what they say is complete nonsense. Note: `Arse' is a very rude word for a person's bottom. He accused an EU aid official of talking out of his arse. Note: Other words such as backside can be used instead of arse. Much as I appreciate today's team, Dennis is talking out of his backside when he says they're the best ever.