Karl Marx face
An unimpressed or unamused, sometimes mildly disgruntled facial expression, generally adorned with a luxurious beard, though this is not mandatory. The term refers to the face Karl Marx had in most of the famous photos of him. This face is not confined to use within contexts referring directly to Marx or his ideas, but it does complement them well. 
"I was displeased with the bougeoisie, so I gave them the Karl Marx face."