Beetlejuicing is when one user posts a comment or thread on reddit, and another user with a username relevant to that parent comment or thread responds.

It is not beetlejuicing if the commenter does not respond "naturally." Summoning someone with /u/ or asking them a question about their username is not beetlejuicing.

When you mention someone's name (typically someone you don't like) a few times in a conversation, and end up running into them a very short time later as though you "conjured" them up by saying their name three times (as in the movie "Beetlejuice".)

A phenomenon often appearing on Reddit. It's when a user posts literally anything and someone with a relevant username posts a reply. Similar to Username Checks Out.

In polyamory, a synonym for being "ghosted," but by a couple you were trying to seduce. In the 1988 film, Beetlejuice, a recently deceased couple, Barbara and Adam Maitland, become ghosts.