There is a button next to shared content (v). Click that and you can hide all reposts from The Onion, MSNBC, Atheist supremacist groups, MoveOn, etc. etc.
I call it Socialist Networking for a reason.
First they came for the Socialists, and I did not speak out
Because I was not a Socialist.
Then they came for the Trade Unionists, and I did not speak out
Because I was not a Trade Unionist.
Then they came for the Jews, and I did not speak out
Because I was not a Jew.
Then they came for meand there was no one left to speak for me.