My MIL once had a total conniption when FIL asked for tomato ketchup with his full english. It was in a pub where we'd stayed a night, and I think she felt cowed by its grandeur. It wasn't grand, she was very insecure, and desperate not to be thought 'common'.
Turn this kind of feeling the other way, and you get strange behaviour from people who believe they know how 'not to be common'.
Sounds like you were eating with some such, Kopend. It says more about them than they think!