How do let people know you need to change your pants

When you had messed you pants, what did you say?
A few I’ve used in the past:
I’ve soiled myself (or pants)
I’ve messed myself
Just done a poo
Couldn’t make it
It was only going to be a fart
I’ve just had an accident
When I was younger:
I’ve been poo poo
I’ve done big jobs
I’ve done poopy plops