The 1900s

I regularly say "from the 20th century" when I want to emphasize the age, the irrelevance, of my lack of knowledge of something.

I don't know crap about cars, so sometimes, someone would ask me about an old one or something and I'd say "not sure, mid-20th century I think".

It's a funny way to talk about it and it almost masks the fact I just tried to get away with a 25-year window.

Although in a more rude manner I'll also say I don't care about some 20th century movie or something.