My sim drank the ghost goo and is now stuck as a ghost?!

When I gave my co-worker ghost goo, it worked immediately, I would have liked to have seen Grim. Also, it lasted several hours, I'm not sure if it was 4 or 6 and then she returned to normal. She also became playful after drinking it (she was purple and it said so when my sim talked to her), even though she was happy just before that. Guess that's a side-effect that's supposed to be there.