"And he had a Cousin Willie
Who played soccer for Caerphilly
When he started playing rugger
He looked such a silly billy"

Is there a technical term for the action in the last line above, i.e. when you put in a different word to the one expected (as in "billy" instead of the expected "bugger")? Although one thinks of "euphemism" or "double entendre", I think these are subtly different.

Whatever this technique is called, I occasionally use it in some of my own (very amateur) songs, e.g.

I met a girl on a Tuesday night, her hair was coloured black
I'd heard from all the men in town, she was good in the ...dance hall

The dots indicate a slight pause before "dancehall" (the audience is presumably expecting to hear "sack" at the end of the 2nd line).

I always think think it is funnier if the rude word is not actually spoken or sung. I wonder is this a very British thing, or does it occur in other English-speaking countries, or indeed elsewhere in Europe or even further afield?