Seems to be hinting at The Babysitter from Netflix. Following the methodology of reversing the number plus 1, converting to a date and matching to American Dad this is season 9 episode 6 - Adventures in Hayleysitting. Could be a fun IP to do, as from memory there’s some very creative kills here
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Edit - having just watched the episode it could also potentially be Halloween 5 (scene involving a roll In the hay in a barn), or Scream or other 90’s slasher (teenagers having a house party).