I had to say pass wind and if you weren't alone, it had to be in the bathroom.
The Scottish word is pump but I'm not sure I like that much either. H and I jokingly call them windy pops (as in "ooh, I've got the windy pops tonight" 
) so probably that. My mother will have a fit. 
She can't cope very well with my friend's son using the word poo. She mentioned one day "he shouted I've done a... well you know, that word his mum lets him use."
It was toilets or the toilet in our house. This was the same woman who would also not let me say bum, knickers, fart, pump, trump, belly, belly button, pee....