I'll try and give you a non-smartass reply. Ref: above posts. What pilots do at work when not flying varies greatly between airframes. It also has to do with what additional job you have. Every pilot in the squadron will have an additional job besides flying. There are several shops common to any flying squadron (wether its pointy nose jets or heavies)...those are scheduling, training, stan-eval, life support, safety). As a brand new dude, expect to be some kind of b!tch boy (snack-o, SELO, scheduler, exec, awards/decs).
How many office hours you work is directly proportional to what job you hold. If you're the snack-o, not much time. If you're lucky enough to be a scheduler or exec, plan on spending quite a bit of time in the office when not flying.
Oh yeah, pilots still drink ON THE JOB when not flying. Beer light is almost always on after lunch.