Geez, Academy of Linguistic Awareness! Either of these would have worked:
Don't sound stupid; stop saying like.
Don't sound stupid. Stop saying like.
Now your cover is blown, and your chances of affecting a perfectly good cause are shot.
This is sadly similar to Stephen Notley's attempt to correct society's greivous apostrophe errors. (He of Bob the Angry Flower fame.) He publishes this insanely brilliant, popular, and world-altering strip:
Bob's Quick Guide to the Apostrophe, you Idiots
But then he blows his cover with this one.
He mistakenly thinks that the name of the competition, the "World's" is incorrectly pluralized, when in fact it is simply the World's Gymnastics Competetion or something like that. There are no multiple "worlds" participating.
To be fair, he fessed up to his error in the annotations of the printed book, and he more than made up for it with a series of other linguistic propaganda leaflets such as this one:
Bob's Quick Guide to French, you Idiots
P.P.S. The "Acadamy [sic] of Linguistic Awareness" is a satirical group. Notice the spelling errors in their poster, not to mention their name. Is the comma splice intentional? I don't know, but one thing is certain: people should stop saying "like" so often.