Shoulder dislocations are one of the most common kinds of shoulder injuries and should be treated by a medical professional (popping it back into place like a character in an action movie is NOT a good idea).
Two different kinds of shoulder dislocations
Shoulder dislocations result from trauma
The vast majority of shoulder dislocations are the results of falls or accidents in sports activities such as:
Short-term treatment
In the few moments after a shoulder dislocation, but before proper medical attention is available, it is helpful to do two things:
Recurring shoulder dislocations
This is bad. Each time this happens, it can cause further damage, even if it seems as if the shoulder can be popped back into place. See a doctor in order to avoid further complications.
Further complications
Left untreated or not treated properly, a shoulder dislocation can become much, much worse.
Prevention
Preventing a shoulder dislocation is worth the small amount of time it takes to put on protective gear when engaging in contact sports or to perform exercises that strengthen the shoulder and make the joints more flexible.