There was a class I took where I'd show up once every two to three weeks since the graded work was all done online. It wasn't uncommon for me to have nightmares about going into class and finding out that it was a test day or that some big unannounced project was due. When I did show up, I'd slink off to the back corner. In one instance, the professor stared at me minutes before class started. I pretended to be all nonchalant and was trying to act like she wasn't eyefucking me. It was uncomfortable. Left there with a B+ though.
In my later years, when the student loan debt was piling up, I went to every class because each lecture was about $20 a pop and felt that I should take advantage of it. Most lectures are useless.