Sometimes I pay attention.
Most of the time, I'm just watching YouTube and waiting for the conversation to either call my name or the class to end.
Like ghoulybits, senioritis has killed my motivation for things that I just don't care about. Music and Japanese class actively keep me up, and I actually want to be there for those moments. Marine Science is interesting, too, but I'm mostly just doing math for "fun facts" (like how many burgers a person would have to eat to match the diet of a minke whale). But I just slack off for the rest of the classes; English, History and Gym. I don't have to try in English or Gym, and History is the class subject I hate with a passion.
TL;DR, it depends on the class.