I did quite well on my last substitution, which I hadn't asked for. I ordered a normal jar of Branston Pickle, not available, and got an extra large one.
When I used to order online from Tesco, I’d ordered a tub of Utterly Butterly. They substituted it with 2 litres of milk, so I asked the guy whether I was expected to jump up and down, holding the milk, until I made my own butter.
I also ordered some fish and they sent a pack of beef mince. Maybe they thought I wanted a sea cow (manatee.)