TL;DR version: Google inserted bogus results for ridiculous search phrases. Amazingly, those bogus results suddently popped up on Bing. Example:
As we see it, this experiment confirms our suspicion that Bing is using some combination of:
Internet Explorer 8, which can send data to Microsoft via its Suggested Sites feature
the Bing Toolbar, which can send data via Microsoft’s Customer Experience Improvement Program
or possibly some other means to send data to Bing on what people search for on Google and the Google search results they click. Those results from Google are then more likely to show up on Bing. Put another way, some Bing results increasingly look like an incomplete, stale version of Google results—a cheap imitation.
I am table-flipping mad! （╯°□°）╯︵ ┻━┻