I've worked in a library for many years, and the weirdest thing that I've seen is someone come into the library to sell steaks--not from a fundraising catalog, but steaks that had obviously just "fallen off a truck." They were a little put out when I kicked them out. I've occasionally caught people getting or about to get sexual, and more often come across evidence of same (pages in certain books stuck together, used condoms in wastebaskets), but that's really not unusual--it was well known at one of the universities that I attended that a certain men's room on one of the less-used floors of the university library was the campus cruising spot.
Also, Marten doing some exercise that built up only his deltoids would make him look like one of those World of Warcraft avatars that are really skinny but have huge shoulder pads. He should look into some basic weightlifting; there's a school of thought that says that, unless you're a bodybuilder, you really only need to do the overhead press, the bench press, and the squat to stay in shape.