Stammer Awareness

These posters from Kekemelodi have been released to help promote the classes run by the company to help people with stammers. Created by DDB Istanbul, these adverts do spark some humour with their clever wordplay, but are they offensive? Buzzfeed posted these a week ago and argued that the ads were insulting to people with stammers and:

The ads are, literally, mocking the shit out of them.

Personally I think they are smart, and the wordplay is great. However I am fortunate enough to never have suffered a speech impediment so I can’t commenting on the “correctness” of the adverts. They have stood out enough to be noticed though which is a key part in advertising.
What’s your thoughts on the subject though? Are these posters harmless or do they cross a line?