I wanted to order Vowelburgers™ as many as possible, and came up with one idea. But for the purposes of giving a puzzle, I'm concealing what the idea was.
Here are the Vowelburgers™ I've received, grouped in a particular way:
Here are the ones with one patty: kilogram, bog, fail, chaos.
Here are the ones that I'm unsure whether they have one patty or two patties: baton, deer.
Here is the one with a colored patty: code.
But there is one group remaining, in which I found two Vowelburgers™. And... yuck! I wish I've never ordered them. Why?