This has kinda been puzzling me for a while. How does Twitter manage to avoid common grammatical phrases or other non-content specific phrases from trending? For example the two words 'I think' or 'that was' etc etc, (although the possibilities there are limitless)

Right now for example, 'Spooks' is trending, which clearly isn't the most prolific word on Twitter right now, it just happens to be relate to relevant content.

I did try to find out the answer on Google but couldn't, so DiS - shoot.