"So, you want me to... hold your hair and angle your head so that your cheek is submerged, but you can still breathe."

He can think of so many ways this could go wrong, but he also can't think of a better approach. Except the straw thing, but, again, that would mean leaving. And also trusting Joker to remember to breathe through the straw and not like... hold it in his mouth and then breathe through his nose or something.