Tensions rise when Lorcan mocks Ruby's new cleaning job in Thursday's Fair City on RTÉ One and the RTÉ Player.
Carol puts her grandson in his place.
"Did your ma never tell you that if you have nothing nice to say, you keep your gob shut?!" she says.
"There's a lot of things that my mum didn't tell me," Lorcan replies.
Fans can find out what happens next on Thursday on RTÉ One and the RTÉ Player at 8:30pm.
Fair City airs on RTÉ One and the RTÉ Player on Sundays, Tuesdays, Thursdays, and Fridays.
