...Marauders When Bored...

James Potter: Never shuts up.Is always fussing around about the most pointless stuff. Or rather keeps fantasizing about Lily.

Sirius Black: Sketches stuff or takes out a spare piece of parchment to write or draw. And if he can't possibly do any of that artistic stuff, he starts annoying the hell out of any person available at the moment.

Remus Lupin: Overthinks or sleeps or makes an effort to utilize his time. And if these efforts do not work, simply leaves himself be (i.e becomes as opposite to real life Remus Lupin as possible).

Peter Pettigrew: Takes out his emergency food stash in order to regain all the energy this pathetically boring day has drained out of him.