Goedam: Season 2, Episode 4
Jae-sung, suffering from a severe toothache, goes to see the dentist Chung-jae. However, the dentist doesn't find any particular causes and asks that Jae-sung comes back tomorrow. Soon after Chung-jae finds something writhing in the sink. Upon further investigation, his gut begins to tell him that nobody will be smiling pretty if Jae-sung returns.