I bet you tripped your circuit breaker or GFCI. Especially with a wobbly outlet.
Check the panel for a tripped breaker. Also check all your other outlets around the outside, garage, utility rooms etc. for a tripped GFCI. It's normal for a GFCI in one place to feed/protect other outlets elsewhere. (hey, outlets are $3, GFCIs are $20, why wouldn't you?)
If you got a breaker trip, the hot wire most likely touched and you may even see scorch marks on whatever hit. If it was a GFCI trip, then you won't see marks, and the neutral screws may also have hit (GFCI detects that too).
First I want to say metal junction boxes are a good thing. Why below.
But outlets are not supposed to be floppy. If it's moving around in the junction box, the screws have loosened up or it's broken. What happened is, the box has screws on the side intended for attaching the wires. Often, builders in a hurry just jab the wires in the back-stab connections, and leave the screws sticking all the way out (at their maximum where they hit their detent; they can be taken farther but it damages the outlet if you do). If the receptacle shifts around, the screws either hit the side of a metal box, or a bare ground wire.
The pro (read: not in a hurry) method is to either use side screws, or a deluxe outlet ($3 instead of 60 cents) where the wires are clamped down by tightening the screws. And tighten down unused screws. Some will also wrap a few turns of electrical tape all the way around the sides of the receptacle, to cover the screws.
Why are metal boxes good? If there is arcing inside a box, they ground it and hopefully trip the breaker. If there's a hotspot, they efficiently conduct the heat away from the hotspot to prevent it starting a fire. A plastic box doesn't conduct heat very well, instead it melts and helps set the wall on fire (it has anti-flame additives so it won't start, but if an external heat source starts it, it will burn -- plastic is made of petroleum.) Once a fire gets started in your walls, it's all over but the shoutin'.