What do you say?
I say neither because I never mention these things.
What is correct english language wise?
If you're doing a poo, you're doing something so that makes sense. Having a poo sounds like you're eating it.. But then we say 'have a shower' don't we? Not do a shower. I don't like when people say 'I'm going to get a shower' (is B&Q open)?
Sorry. I'm having a day off from life today and this just sprang into my head. Humour me please.