The least offensive swearwords...

[K@]

...are, apparently, "Fuck" and "Shit".

As we all, if we're lucky, fuck and, unless we're particularly unlucky, shit, they're not discriminatory and, therefor, less offensive.

[Tâf]

Unless you call some a lazy shit or a lazy fuck? Or whatever.

Arse is a pre-watershed word for the BBC now too.

[Izzy]

And the most offensive?

[K@]

I guess it depends on who's being sworn at/to...