Only problem with that word I see is that everybody is a general enough term to include all life forms, not just humans.

She also knows that humans are not ponies either.

If you believe you or another user on this site is a pony, then you are poorly misguided in life.

Those are ponies in the gif, and it says everybody not everypony, if you can't see the obvious don't reply.

But Derpy was breaking the fourth wall and telling us to.

I'm almost certain ponies have bodies, so "everybody" would also refer to them

everybody is defined as 'every person'. yes they have bodies, but if we wanted that to be correct it would have to be every body, which would further complicate things by having water bodies all over flopping around.

"Every person" is abbreviated everyson (It's chinese)
"Everybody" is every entity with a body - which also includes robots that can think for themselves