It contains the advice or opinions of one or more Wikipedia contributors. Essays are notWikipedia policies or guidelines. Some essays represent widespread norms; others only represent minority viewpoints.
Following editors to articles they are editing during an unrelated dispute
Adding wikibreak/retired tags to userpages of other users without their consent
Adding block templates to a blocked user's page or talk page if the blocking admin has not
Having been asked not to (or otherwise knowing it is unwelcome), continuing to post on a user's talk page
Fussing with another user's userspace
Nominating all articles created by a user you have a dispute with for deletion
Repeatedly informing others about past block(s) of a user you have a dispute with
Telling an editor "I don't know how many times I have to say this" after having said it only once and receiving a reasonable response
Suggesting an interaction ban over dispute with a new user, effectively topic-banning the established editor from their article niche
Addressing an editor you're not on particularly good terms with as "dude"
Implying an editor may have mental health problems with the patronizing assurance "There is no conspiracy here."
Telling an editor holding a minority position with conviction "Perhaps you're not suited to working on a collaborative editing project."
Supposing an editor who has irritated an Administrator is seeking "death by cop" or "suicide by Admin"
Suggesting to others that two editors in consensus over a point of contention with you are meatpuppets or sockpuppets
Commenting to others about a proven editor whom you don't like "Wikipedia is better off without [that user]." (or its equivalent: "[That user] is not here to help build the encyclopedia.")
Addressing an editor as "Friend", or offering them "friendly advice", when the opposite is meant
Dismissing a user's considered thoughts out-of-hand by calling them "a wall of text" (or equivalently: "too long; didn't read")
Using the thank tool to spam an editor
This metaphor could mean more than you intended
Be careful not to imply that a specific individual is a bear. In Russia "bear" may be a compliment, but elsewhere(OED) it can mean a rough or bad-mannered person and "like a bear with a sore head" means very irritable. Using "don't poke the bear" to hint that an editor is over-sensitive on a subject might not be true, and could be construed as a personal attack. You might also offend fellow editors if they think you are accusing them of "bear-baiting" – a bloodsport which involved setting dogs to attack a captive bear.(OED) "Bear" is also a slang term for a big, hairy gay man.