Thanks but no thanks

I've just got in from my book group meeting. I was late arriving there as I'd been at another meeting before that, so I completely missed out on discussing the book (The Art of Racing in the Rain by Garth Stein) and instead got to join in the food conversation that often follows on these occasions. We fell to talking about sweet potatoes, and it was revealed that traditionally at Thanksgiving Americans serve sweet potatoes with marshmallows. I must have looked so horrified that everyone laughed, so to be sporting I tried to come up with some equally revolting-sounding British delicacy - but couldn't think of anything. Help me out!