while others necessarily encourage much more rapid transformations — as occurs when we play a game of “telephone” and each person passing along a message changes it in some way. So, it makes little sense to talk about “memes” as an all-purpose unit of thought without regard to the medium and processes of cultural transmission being described.
Memes aren't a single thought because while the picture may be the same, the words are constantly changing. The picture may even be manipulated, like in the anti smoking commercial that always plays on tv. Memes can be formed and changed to fit any situation in life which makes them so popular.