This seems to be more serious that what have been suggested by other comments.
Luckily one of the girls didn’t like the smoothie and didn’t take much. She didn’t fall into deep sleep and was the one who suspected something fishy going on when the man kept coming to the basement. The man even tried to separate the girls. Again, the girl protected her friends by pulling them closer to her. She finally managed to contact her family friend, when the man went outside, messaging them to come and bring her home, and once she was saved, the other families followed suit.
Given a different scenario where everyone took the smoothies, I speculate with high degree of confidence someone would get sexually assaulted or worse.