The Baader-Meinhof Phenomenon occurs when a person, after having learned some (usually obscure) fact, word, phrase, or other item for the first time, encounters that item again, perhaps several times, shortly after having learned it... unintentionally coined by readers of the St. Paul Pioneer Press ... a reader submitted a story about how he or she first heard about the Baader-Meinhof Gang and then heard about it again a short while later from a totally different source... There are several theories about the psychological explanation of the phenomenon, including a popular one that cites as its primary cause the recency effect, in which the human brain has a bias that lends increased prominence to new or recently acquired information.
I find that once you have heard about the phenomenon, it will occur as a meta-phenomenon. That is, having heard about the B-M effect, you will notice not only a run of synchronous occurrences constituting a B-M effect, but a run of BM-effects.
A BM-phenomenon happened to me recently after I watched In Bruges. Much of that action in that film centred on the tower of Bruges cathedral. I then listened on audio to the second half of Cloud Atlas, the penultimate part of which was set in Bruges, with much of the action taking place in the cathedral tower. Next I visited my mum, and noticed a framed picture she has owned since before I was born. That tower looked familiar. I looked closer at the artist's initials, next to them was written the tiny word Brugge; I assume that means 'Bruges' in Flemish. The picture was of the tower of Bruges cathedral.