Outspoken MP Mhairi Black appeared to let her frustration at a Tory minister show when the pair clashed in a debate on housing benefit.
She was caught on camera mouthing what looked like “you talk shite, hen” in a heated clash over the proposed withdrawal of allowances for 18 to 21-year-olds.
Black, 22 and Parliament’s youngest MP, posted a video of the exchange with Caroline Nokes on Monday.
In it she attacked the “ludicrous legislation” that would see young unemployed adults forced to live with their parents or pay their own rent.
“This government seems to be working on the incorrect assumption that you can simply stay at home when parents have no obligation to house their adult children,” she scolded.
After speaking her mind to the minister, Black sat back down, but was clearly none too pleased with her response.
Nokes hit back, saying: “The Scottish Government already has a wide range of powers which would enable them to alleviate the changes proposed here.
“Our government is committed to working with the Scottish Government on a whole range of issues in the DWP portfolio to make sure they have the strength to implement those powers.”
At this point, the TV camera in the House of Commons cut to a dissatisfied Black, who mouthed a sentence at the minister many believe was probably unparliamentary.
But the reaction wasn’t universally positive on Scottish Twitter.
Some MPs have form with swearing in the Commons. In May last year, Labour’s then shadow defence secretary Emily Thornberry mouthed “bollocks” across the Commons chamber at David Cameron.
The Huffington Post UK contacted Black for clarification but did not receive a reply at the time of publication.