I can not think about the name of this movie, but I remember a short vauge summary/scene of the movie. It's kind of an old or oldish horror. Okay so:
This blonde teen chick turns out to be an alien or something and she comes out of the pool naked in human form but scaring her (teenage) friends causing them to run. (And I think, pretty sure, she had a needle/shot/vaccine thing to turn them into aliens too) and she was chasing them in the pool area and locker rooms.

PLEASE HELP ME!!

-Brittany- <3

The movie is called faculty