I have to pee a lot these days. Before I had a kid, or rather, before we started potty-training, if I had to leave a meeting early or something at work to use the restroom (if looked askance), I would say, “I had/need to use the restroom.” Then came potty training and a lot more comfort with bodily functions, and I say, “I gotta/hadta pee,” or occasionally, “I haveta go potty.” Which is silly and unprofessional, but pretty much all my colleagues are at that point as well.
Back in college, I would say, “I must needs micturate” because in college one can say things like that.
Growing up, we would use the euphemisms “big” and “little” for #2 and #1 respectively. DH’s family uses the standard poo and pee so we went with that. My grandma would always talk about her dogs widdling (whereas our cat “used the litterbox.”)
Here are some options from #2:
What words do you use for pee? Have they changed throughout your life?