Attention! This post does contain some actual swearing. Posted this to Tumblr earlier, where it was well-received. Thought I'd share with the community as well.
There are a lot of comparatively mild curse words that we just accept as being family friendly without much thought as to where they come from. Some are just milder versions of a word we consider unacceptable, such as saying 'crap' instead of 'shit' or 'darn' instead of 'damn'. Others have so completely lost their original meanings that no one even considers them anymore. Here are some fairly common British ones, with pop-culture examples for your enjoyment:
n. One who masturbates; same as wanker.
'Who's Harry Potter?' 'Oh, no one. Bit of a tosser, really.'
—Harry Potter and the Half-Blood Prince (seen by millions of children)
v. To sodomise someone
n. One who sodomises
'Bludgers. Nasty little buggers.'
—Harry Potter and the Philosopher’s Stone (Again, seen by millions of children)
'Sod this, you stay here if you want. On your own.'
—Sherlock, S02E03: The Reichenbach Fall (prime time TV)
n. Short for ‘Berkley Hunt’ or ‘Berkshire Hunt’, which is Cockney rhyming slang for ‘cunt’.
'Then what the hell did you tackle me for, you berk?'
—Rupert Giles, Buffy the Vampire Slayer
And there are so many more. Like, how many people who use the word 'douchebag' actually think about what that originally entailed?