This has been bothering me and none of my friends can remember, either. There was a movie, I believe I’ve watched it within the last year so probably a more recent film (2005-2015), and I believe in the horror genre.
A character is walking somewhere alone and quiet, when suddenly a small creepy person comes up to the character and says “Tag! You’re it!” then runs away. I know this is very vague but if anyone remembers this please let me know, it’s been driving me crazy!