This is a cultural thing. If you must spend time with British people (or some of the ex-colonies) you need to learn how to recognise (and protect yourself from) sarcasm and "jokes" (what you might see as lies and cruelty).

When I was 21 in the US we played a mean game of seeing what we could make Americans believe - and we came up with some truly bizarre stuff.

I think that English people do this as a proxy test of intelligence - it is a continuous competition. Maybe an English person can correct me?