Oh dear. So many people on here aren't familiar with euphemisms for rude things but I know 'em all, and more.... My grown up children have enlightened me on all such matters.
Years ago, my DH was mortified when I advised him to stop calling his boss "a wanker" when they were joking together. I explained what it meant, and it turned out that he thought it meant the same as "a wally." He said, "Oh no! I've called him a wanker, lots of times, to his wife!" In his defence, English isn't his first language.
I think that there are very many things that we assume everyone knows about, but younger people don't. I find myself on the verge of referring to some famous person and then realising it was years since they were famous, and my children and grandchildren won't know who they are.