It didn't have anything to do with Muggles at all! Mikey was missing his point entirely. Maybe he didn't even actually have a point. he liked to pretend that he did, though.
"I don't want the pie," Adam said vaguely, even though his hands were already moving toward it. His hand, actually. The other one was currently occupied with the bottle he and Mikey had been rapidly consuming. He totally wanted the pie. He could tell himself he didn't want pie until he turned blue but he wanted the pie. "Why under the table?" Adam asked. Then he said what they were obviously both thinking. "Will you even fit under the table in that thing?" Mikey was just so very, very puffy.
Adam slowly handed over the bottle, keeping his eye on the pie. "Cake? Who said anything about cake? I thought you were getting the trifle?" Adam was suddenly very confused.