Dr. Alien is a 1989 sci-fi comedy film starring Judy Landers, Billy Jacoby, and Olivia Barash. Directed by David DeCoteau, the film was also released under the titles I Was a Teenage Sex Maniac and I Was a Teenage Sex Mutant. The alternative titles explain the movie's plot.
Dr. Ackerman (Troy Donahue) is the high school biology teacher. Leaving school one night he crashes his car after encountering UFO. Wesley Littlejohn (Billy Jacoby) is a geek who is in Dr. Ackerman's class, along with his opportunistic friend Marvin (Stuart Fratkin). Wesley is the stereotypical geek who is bullied at school and relies on Marvin to defuse situations with the bullies. He is also in love with Leanne (Olivia Barash), but is too shy to make any kind of approach to her.
Instead of Dr. Ackerman teaching biology that day, a sexy, blond-haired substitute teacher named Ms. Xenobia (Judy Landers) arrives and informs the class she will be teaching for the time being. All the males in the class are stunned at having such a sexy woman as a teacher, apart from Wesley. Looking for a participant in an experiment, all the males in class volunteer but Ms. Xenobia selects Wesley and asks him to attend after school has finished.
Wesley goes back to the class after school, where he encounters Drax, Ms. Xenobia's assistant (Raymond O'Connor). Ms. Xenobia arrives and explains that the experiment involves being injected with a vitamin supplement and observing Wesley's reaction. Wesley does not want to participate and Ms. Xenobia agrees, before injecting him with the "supplement" when his back is turned. Out of Wesley's head, a phallic like stalk starts to emerge which excites Ms. Xenobia. She proceeds to have sex with Wesley (who is oblivious to his surroundings) with Drax recording the findings. After the "experiment" Wesley is sent home.
At home Wesley's parents and brother start to see changes in him. He becomes more confident and assured which allows him to get closer to Olivia. However after the experiment there is a tendency for the stalk to emerge at the most incovienent times, usually when there are other woman around. This leads to several sexual encounters, notably with a former bully's girlfriend and the female gym teacher (Edy Williams). Each time these encounters happen, Wesley is left with amnesia and he starts to suspect Ms. Xenobia has given him something more then vitamin supplement. Challenging Ms. Xenobia on the experiments, he is injected again with serum by Drax and again has sex with Ms. Xenobia.
Away from school, Wesley becomes the singer of a heavy metal band called the Sex Mutants (before he played classical piano). He also goes on a date with Leanne although it is interrupted by the stalk which leads Leanne to become passionate with him before "waking up" and accusing Wesley of trying things on too fast. Wesley protests his innocence later on and invites her to a gig that the Sex Mutants are playing at.
The Sex Mutants play their gig, along with support from the Poon Tangs (an all girl group featuring Ginger Lynn Allen and Linnea Quigley). After the show has finished, Wesley is backstage with the Poon Tangs when Leanne arrives. Shocked that Wesley appears to be flirting with the girls, she runs off and Wesley follows her. Outside the venue, Ms. Xenobia is waiting for Wesley. Wearing a silver spacesuit she informs Wesley that she is in fact an alien who had been experimenting on him to help her race. The males of her species lost the ability to procreate and she was tasked with finding the cure. With humans having a similar biology to her species, she landed on earth and began her experiments with Wesley. Wesley does not believe this and tells Ms. Xenobia that she is crazy. Ms. Xenobia then proceeds to peel off her face, revealing that it was a mask covering her true identity. Rather than a sexy woman, she is revealed to have a large blue head. Wesley panics and runs off (not before throwing Ms. Xenobia into a garbage can).
Wesley returns to the school (encountering Drax) where he blows up the biology lab, destroying Ms. Xenobias serum. Ms. Xenobia meanwhile starts to shoot up the music venue with a ray gun. Wesley arrives and threatens to drop the last batch of serum unless Ms. Xenobia stops her violent spree. Refusing to do so, Wesley destroys the serum, shocking Ms. Xenobia enough that she stops shooting. Despondent that the chances of saving her race are over, Drax appears with a stalk growing from his head. He had taken some of the serum because he was in love with Ms. Xenobia. This allows Ms. Xenobia to have a change of heart and she apologises for all the hassle she caused Wesley. Wesley is also able to reconcile with Leanne. In the end Ms. Xenobia and Drax head home to their planet, while Wesley continues his new career with the Sex Mutants.
Judy Landers as Ms. Xenobia
Billy Jacoby as Wesley Littlejohn
Olivia Barash as Leeanne
Troy Donahue as Dr. Ackerman
Stuart Fratkin as Marvin
Arlene Golonka as Mom
Jim Hackett as Dad
Bobby Jayne as Bradford Littlejohn
Raymond O'Connor as Drax
Ginger Lynn Allen as Rocker Chick #1
Michelle Bauer as Coed #1
Linnea Quigley as Rocker Chick #2
Edy Williams as Buckmeister