What are those memes called?

[olaph]

The correct term is De-motivational posters as they are an internet meme ripping on those Motivational posters people like to put up in their office cubicles.

[olaph]

ACTUALLY, they started at despair.com, where people could actually order de-motivational posters for their office, and people capitalized on that and started using them on the internet.

The fact people bought them online doesn't change what I said, you are merely arguing semantics.