I dont know if i would call these weird habits, but when i edit a post online, i almost always put "Post Edit" on an edit post mainly because it reminds of "Postscript", and how once you finished a letter you would write "P.S." to add in you thought so I applied the same to forum post.
The other two are pretty well known and is often seen, but i often in times hardly capitalized i in a sentence. I know my English grammar rule, you are supposed to do, but in my mind, I can't rationalize it since he, she, and they are capitalized as well. The other thing is never using a ' to make a contracted word, most of the time, like don't, won't, and so on, and I have no reason why for this one. I have just always done it, and the only thing I have came up for why is because when I learned cursive you write all the letters together so.
I'll watch it and think "she would never fuck that guy in real life."
Never think that because with enough money anybody can get laid