_bell can't be unrung_?

[Sam Clements]

OK.  I've been asleep.  I just read a thread over at Straightdope, where a poster said "of course, the bell can't be unrung now."   That by itself wouldn't have caused me to wonder, but I  heard an interview on NPR this morning where virtually the same phrase was used(which obviously stayed in my mind).

I understand the meaning.  But, did someone just send out instructions by email that this is the phrase for May, or am I just living in my own little world.  Some of you who read more/listen more than I may know.  Any ideas who must have kicked off the (soon-to-be overused) phrase recently?

Sam Clements