Green’s Dictionary of Slang

a dismissive, sarcastic phr. ‘sure, I (don’t) believe you’.

1977		W.D. Myers Mojo and the Russians 38: ‘We could take the subway,’ Anthony volunteered. ‘Right, and then get off at every stop and ask everybody if they’ve seen two Russians drive by, right?’.
1996		T. Wolff ‘The Life of the Body’ in The Night in Question 48: ‘They were black, right?’ ‘Who?’ ‘The guys that jumped you. [...]’ ‘I don’t know,’ he said. ‘Yeah, right,’ Robbins said.
2003		McGill Reed Dict. of N.Z. Sl. 237: Yeah, right Derisively sceptical catchphrase [...] e.g., ‘The bach sleeps four, max.’ ‘Yeah, right.’.
2003		‘The Simpsons’ quoted in Guardian 20 Apr. 🌐 homer: ‘Lisa, honey, are you saying you’re never going to eat any animal again? What about bacon?’ lisa: ‘No.’ homer: ‘Ham?’ lisa: ‘No.’ homer: ‘Pork chops?’ lisa: ‘Dad! Those all come from the same animal!’ homer: [chuckles] Yeah, right Lisa. A wonderful, magical animal.
2004		J.A. Juarez Brotherhood of Corruption 13: [H]e definitely didn’t enjoy being told how to raise his kid. He said ‘yeah, yeah’ to the cops.