u/KinderEggSkillIssue

In the 10th Anniversary teaser, the voice narrating sounds Irish and this is sounds like Stitches the clown from "Stitches". Also, the birthdays and the imagery of the way the teaser was filmed makes me think "Longlegs" might be possible, and the way they say happy birthday like in "Longlegs" also adds that theory for me, but I don't know if I'm diving into that one too much, so idk how likely that is.