My hobby :

Showing people in the bay area this photograph and asking them if they've seen the new Apple HQ

https://en.wikipedia.org/wiki/Government_Communications_Head...

a.k.a "The Doughnut" because of the shape of the building: [0]

// For non-Brits, 'doughnut' = 'donut'

[0] https://en.wikipedia.org/wiki/The_Doughnut

Ah sorry, I figured that after all the Snowden leaks the intelligence service acronyms were widely known on HN. GHCQ were particularly prominent in many of the leaks