Thank him? Forget crazy, he was BRAINLESS. "Thank you? More like you can FUCK OFF," she shrieked as she pushed her hair back out of her face. The cold water was clearing the fog of drunkenness somewhat, but the point of the alcohol from the Harry Potter world was that, unlike with normal alcohol that her system metabolized quickly and healed any 'damage' from near-instantly, the magic was unaffected by her abilities and responded sluggishly to the quick-sober gestures of coffee or cold-as-ice water.
But he had no intention of letting that stop her, especially because she didn't want to be sober. Right now her mind was fully on what he was doing, but when there was nothing more pressing to think about in sobriety, she would think about everything else. She didn't want to think about that. She just wanted to sleep.
So she slipped and slid in an attempt to get up, the skin of her palms provided no more traction than the fabric twisted around her feet had. No matter which way she went in an attempt to get her feet back under her, it didn't work.
It only made her more furious.
"I never, NEVER, threw FREEZING COLD WATER on you when YOU WERE DRINKING YOURSELF TO SLEEP," she said, tone fluctuating from angry raised voice to shriller, the edges of words still slightly fuzzy in pronunciation. "Which you did a LOT of, let me TELL YOU, so take your BOYSCOUT JUDGEMENT and… AND DO SOMETHING UNFUN WITH IT."