Everyone was asleep in Asgard, which naturally made it a good time for Loki to run around being a dick. This asshole, up at way-too-fucking-late-o’clock decided that the only reasonable thing to do in this situation was to go piss off people he couldn’t handle, because no one ever told him not to pick fights he couldn’t handle. So what does this asshole do? He sneaks into Sif’s room while she’s asleep and cuts her fucking hair off. Why? Because he fucking could. To be a dick, he drops all the hair in a big pile on the floor and traipses the fuck off to go to sleep now that his work is done.