An assignment (typically for school) that is given for the sake of having an assignment.
Bullshit assignments relate to the course, but they do not particularly advance your knowledge in said course. Since these assignments are not useful for actually learning, they are bullshit assignments. It is just a bunch of busy work that makes life more frustrating than it already is... Especially since the assignment shouldn't exist in the first place!
Some courses require essentially no homework. The teachers will begin to feel as if they are doing a poor job because of this, and in effect, will create a totally bullshit assignment in order to justify their lack of assignments.