Taking a 4-year-old to Do His Business

Him: I have to go potty.  
I don't have to go potty.
(We walk into the amusement park women's public restroom, pick a stall.)
I want a *big* potty. This is a (s)mall potty.
Me: This is the only size they have.
(Pulling out seat-cover)
Him: Don't put the paper on the seat!
(Sliding onto seat, facing side.)
Look, there's a handle! (Patting bar on stall wall)
Me, quietly: Make sure your penis is pointing down.
Him, not quietly: It is! My penis is pointing down! My penis is pointing down, Mom!
(turning to look at the back of the toilet)
Is it going to flush me?
(which sets off the auto-flush, which sprays...everything)
Ah! (jumps off) 
It flushed me, Mommy! 
(I wipe seat off with toilet paper, cover auto-flush sensor with my right hand.
He scoots back onto the seat, holding side bar so he won't fall in.)
Hold my hand, Mommy. 
(He grabs my left hand with his left.)
We hold hands on the potty. We hold hands.
(I melt.)
Is it going to flush me?
Me: No - see I'm covering the sensor. (Performing a little-known yoga position, holding his hand with my left while stretching my right hand around him to cover the back toilet sensor without touching any walls.)
Him: Don't cover the whole thing! It's going to flush me!
Me: I'm not covering the button, just the sensor.
Him: It won't flush?
(Someone flushes nearby; he jumps off, destabilizing my perch, looks back down to be sure it's not his potty.)
Who is that?
(He squats down to look under the stall walls.)
Me: I don't know. Don't look under there. Are you done?
Him: No. 
(He hops back on potty.
Pee escapes between seat and toilet bowl onto floor.)
Him: Oh no, Mom! The floor is getting wet!
Me: I see. We'll clean it up when you're done.
Him: The wet got on my pants!
Me: It's not too bad. We'll be going home soon. You'll just have to wear them for now. Are you done?
Him: No, I won't be done till The End, Mom.
(long pause)
(Potty noises echo from another stall.)
What is that sound?!
(There is no good way to answer this question when the noise-maker can hear you.)
Someone's burping! Who is that!?
Me: I don't know. The fireworks are starting! Are you done?
Him: No, it's not The End yet, Mom.
(long pause)
(He starts opening and closing the lid of the stall-wall trash can in front of his face with his right hand.)
Why is there a trash can here?
Me: Don't touch the trash can; it's yucky.
Him, pointing to the little picture on the stall-wall trash can: The hand is putting the toilet paper in the potty. It's a funny potty.
Me: I think it's just telling us to put any paper in a trash can or toilet.
Him: Yeah, toilet paper does not go on the floor. Last time, there was toilet paper on the floor, and I don't know how it got there. (He peeks into trash can.) There's something in there! What's in there?
(starts to reach his hand in)
Me, dropping his left hand to swat his right hand away from the trash can: Trash. Yucky. Are you all done?
Him, hopping off the toilet: Yes. Now wipe my penis.
Me: You can do it.
Him, turning and bending to show me his backside: Is all the poop off?
Get all the poop off!
Me: You can do it.
Him: NO! I want you to do it! I can't wipe every day. I just wipe on one day, and so much days, but not some days. You wipe.
Me: No, you can do it.
(Him grabbing one square of toilet paper, wiping in the general vicinity. 
Me trying not to think about how insufficient that was.
Him struggling to pull rolled underwear and pants back up, touching every surface.
Me wiping floor with wads of toilet paper.
Toilet flushes, spraying both of us.)
It's flushing! It's flushing!
Me: Time to go!
(Walk to sink)
I can't reach!
(Sitting on my knee)
It's too hot! Make it cold!
My shirt is wet.
I can't reach the soap.
There's still soap on my hands. See? Look.
(We exit, 20+ minutes after we entered.)
Him, grabbing my hand, pointing with the other: Mommy, fireworks! They're bootiful!
Me, smiling: Yes. They sure are.