You can also swing one on a cable as an effective anti-burglar weapon.
And that's its problem: it's bloody massive. On our recent trip, we had a bunch of universal plug adaptors with us, and for one item we took the Euro mains lead, because it was lighter than the UK plug lead and we'd be able to use it anyway.
So it was with some interest that we encountered the Australian socket for the first time. For our adaptors, using a .au socket meant bringing out the US two blade section, and gently twisting the blades so they were angled apart. And into the socket and hey - unlike the US case itself, where the weight of the adaptor would pull the whole thing down, these stayed where put.
The downside was that on a double socket, we couldn't get two in - the sockets are set much closer together. Happily, there were enough sockets around we could always make use of three adaptors.
(As for HK - they use the Type G - so we used the adaptors for that Euro lead).