Neat, I've never seen that version before. The one I know is:

Johnny was a chemist's son
but Johnny is no more.
What Johnny thought was H2O
was H2SO4.

Fun fact: unlike some other site that shall not be named, Lemmy's markdown can do subscripts!

Little Johnny took a drink
but now will drink no more
For what he thought was H2O
was H2SO4

Strong acids are weak, you'd notice the boiling acid flavor and spit it out with the rest of your mouth lining right away.

Doubt you'd die from drinking a bit of sulphuric acid, probably would spit it out as soon as you notice your tongue is burning anyway.