One time at band camp, me and a bunch of other woodwinds had to stop the senior male brass players from giving a newbie a swirlie. It didn't help that the kid was willingly going along with them because he thought a swirlie was a chocolate/vanilla ice cream cone.
On the blood topic, it's weird watching people get woozy over blood. I'm stuck by so many needles, that it just doesn't bother me. I got an iron infusion a couple years ago(they were done in the same room as chemo therapy in the hospital), and the only fainters were family members of patients.