Your idea of urine is too limited*

The three and one half year old human uses JJ Abrahams logic* on me in the john.

3.5 yr old: DAAAAAAAAAD
Me: [poking head in to the bathroom] Yes.
3.5: I'm done. [pulls shorts up over legs, leaving vital area exposed, saunters past me to harass dog]
Me: What happened here? [I'm inspecting the toilet area incredulously]
3.5: huh?
Me: What is that covering everything?
3.5: Um, I think that's pee.
Me: Great. when did this happen?
3.5: That was... Um... I did that.

...but I didn't do it today.

Me: OK. When did you do it then.
3.5: Tomorrow

Busted.

The three year old has learned to deploy language and sensory perception to get what is important in life.

DaDa! [hug]. 

[brings face in, close] [sniffs], "I want choclit.You smell like choclit; I want some"