Inspired by seeing a can of ghee for sale in my local Coles, I started mentally listing things I've never cooked/cooked with:
livers from any creature
kidneys from any creature
My Mum used to cook lamb's fry (liver) in a pressure cooker when I was a kid, and I didn't mind it in small quantities. I seem to recall it make for a particularly delicious gravy. She also did steak and kidney stew, and again, kidneys in small amounts were OK. But can't say I have had much inclination to try eating them again (pate excepted.)
I haven't been paying close attention to My Kitchen Rules this season - I agree with some critic somewhere who said that the "drama" element of the show has been pumped up more and more every season, and it's now more the point than the cooking. From some advertisement I half watched last night, it looks like the show will soon feature a disaster of some kind - was that a contestant or two lying on the yard with an ambulance in attendance? Come on, this is getting very silly.
Anyway, I did see part of it recently where, once again, the cooks were served bone marrow as an entry.
Don't know why, but I find the idea of eating the jelly like, fatty substance by itself just really off-putting. Even though, when cooking ossu bucco, it is probably the melted marrow which makes the surrounding stew so good. Some cooks love it, though.