Because you can't "accidentally" shove someone with your foot, Zoey.

Setting: Mommy's car, on the way home from daycare on Monday

Me: How was school today, bug?

Zoey: Good. I pwayed. (This could mean 'played' or 'prayed'. Either option is standard daycare material. I was fishing for something more interesting, to be honest.)

Me: Soooo...what did you play?

Zoey: *Pause* Destiny went down the yellow shwide (slide) on the pwayground.

Me: Um. Okay. That's...nice.

Zoey: 'Cause I pushed her.

Me: ZOEY. You pushed her? Why? Pushing isn't nice!

Zoey: (Matter-of-factly) No, Mommy! It was an accident! I just pushed her with my foot! On accident!

I'll bet you twenty bucks it was no "accident". Just because my child feels free to barrel down any slide, any time, face first, with no regard for her own personal safety, she expects this same caliber of behavior from her friends. Another twenty bucks says the way the situation ACTUALLY played out was Destiny working up the nerve to propel herself down the slide, Zoey deciding Destiny had had quite enough time to work up her nerve, and giving her a nice shove with her big ol' foot. You know. On accident.