It's Christmas day. Mum has made a fantastic Christmas dinner. The boys are delighted that Grandma, is coming round, but horrified that dad's (Martin's) mother - 'Horrible Grandma' - is coming too. Horrible Grandma turns up with her equally horrible dog, Boudacea, which has to wear an oxygen mask. Horrible Grandma hates mum's 'horrible dry turkey', and mum is distraught when Horrible Grandma brings her own turkey with her to eat. Dad and the boys are jealous, as they too secretly hate mum's dry turkey. After dinner, tensions mount, as the two grandmas have an argument that develops into a proper grandma fight. And then Jim turns up, dressed as Father Christmas... (thetvdb.com)