Mysterious Black Liquid

What's that black liquid
Steaming in Daddy's cup?
It smells super good
And Dad drinks it all up.

It must taste yummy,
Dad smiles after one sip.
I want to try it,
But I don't want burnt lips.

Oh good, Dad's out back.
His cup has just enough...

Just one sip - SLURP - Yuck!
Dad drinks some nasty stuff!