A Stool

In the bathroom at a fast food place,

 washing my hands

With my helper,

as always.

Him: I wanna wash too!

Me: OK, let me dry my hands and I'll pick you up.

He steps on my big toe with all his weight,

leaving me locked frozen in pain.

Me, frantic: Ah, Ah, Ah!  You're standing on my toe!

Him, totally calm:  Yes.  I use it for a stool.