So, I phoned the emergency vet and told him my, or rather Wuppie's story and here is his view on things: it is as I suspected an ear hematoma, most likely caused by an ear infection (which would also explain his dizziness a week ago). He would shake his head because of some minor pain and that's probably how a blood vessel burst, flooding the space between the two flaps that make up his ear. An operation can be done, but it would have to wait for several days up to a week for the blood to partly drain away naturally again, because they can't operate when the ear is bleeding. But if it goes away naturally the only reason to do an operation would be cosmetic.
Which brings me to the vegetable in the title. When the blood has drained from his ear again, the ear will not return to what it was. Instead it will look like a shriveled up ear, much like a cauliflower. And I am not forking out money for that, after all, it's cosmetic and he is not a showcat! So, there it is, a veggie cat in the making!!
Oh, and before you all yell: but what about the ear infection? Tomorrow morning I will make an appointment with the vet to have that seen to and probably get some anti-biotics.