I bring her water in an open cup, and offer it to her,
"You just asked for water, don't you want it now?"
"You want a hat?"
At which point we realise she wants the sippy lid for the cup. It's a hat for the cup! Sure enough, we put the lid on and she takes the cup and drinks happily.
p.s. Now when I fart, daughter says, "far!" and laughs. Hooray.