Three years ago, I moved into my apartment. The next day, the neighbor from the downstairs apartment (8A) began visiting me and leaving notes.

These are some of those notes.

MERRY CHRISTMAS from my neighbor! I caught her putting this one in my door. I happened to be walking by and heard it going in. 
ME: *opens door*
HER: There’s your note.
ME: *picks up note* I’ll call security now.
HER: B**ch.
ME: I hope you get help.
HER: You’re a sick b**ch.
(As it happens, last night was the first night I slept all the way through since the surgery. But I’m looking in the mirror anyway. LOOK IN THE MIRROR!!!)
Just back from the doctor for my post-op checkup and found this under the door! 8A is more right than she KNOWS! Again, this note has come after the cease and desist letter from the legal department, which I think accounts for the nice handwriting. 
This is not a note from 8A, and was not found under my door—rather, this was a note left in the lobby by one of the children in the building. This is the kind of thing I would like to see MORE OFTEN. Also, I saw this note and said YES.

A note from January 4, 2010, back when 8A and I were just getting to know one another. I moved in on November 1, 2009, and she had come to my door pretty much non-stop for two months. Security had told her to quit it, so she started leaving all these notes about “chair glides.” So many notes about “chair glides.” 

Attached is a reply I wrote BUT DID NOT GIVE TO HER. It was purely a thought experiment. 

Ah, back then, I thought this was temporary. Little did I know…

A note pulled off Twitter from January 6, 2010. Back then, she was very much finding her style. Printed? Handwritten? SCARY RED MARKER? LOTS OF QUESTION MARKS???? Back in those days, she was convinced that I moved furniture from midnight to 4AM. Many notes reflected this. 
An older note I found in the files, from about a year ago. This one was duct taped to my door. I believe this one actually came from the old man in 7A, who is almost entirely senile and quite sweet. He is very much under the sway of 8A. 7A came to my door right after this note was found and asked to come inside to see if I had “threshing equipment.” I do not keep threshing equipment in my apartment, and was happy to demonstrate this fact. He told me that he had been told by 8A that I had an exercise machine and threshing equipment. Satisfied that I did not, he went away and never returned.
This note was so polite I was actually worried about 8A, but then security told me that she’d been issued a Cease and Desist letter, telling her to stop coming to my door and leaving notes. So I guess this is her way of Ceasing and Desisting. 

The followup to the December 4th, post-surgery note. This one was from December 6th. It came under the door as the three of us were playing cards at the table in the morning (because I was recovering and practicing sitting upright in a chair). Again, the mention of doctors makes me wonder if my neighbor somehow knew I was ill, and was trying to find a way to say that she cared! 

This note was found around midnight, December 4th, 2012. I was returning with my mother and my companion from the hospital. I had abdominal surgery that day. So the comment about the doctor is weirdly on the mark, as is the followup, which came two days later. (Also, I believe she uses the word “harassment” because that is what I (politely) accused her of when I found her standing by my door screaming just three days before this.)
I found this note after returning from several days away. It’s very much a classic of its kind. I call it the “bang in the basement” note.