How. Very. Random.

I was cleaning the sink and noticed there was something rattling about in the sink plughole. On closer inspection I found it was a coin. Which is an odd thing to have in the plughole of your sink anyway, but this one was a strange colour - kind of yellowish - and had twelve corners.

Taking it out, I found it was a threepenny piece. From 1944.

This coin is the same age as my mum. How on earth did it end up in our sink?