Beckett: The Irony is it never would have connected them. We don't go through a victim's mail unless there's probable cause and a warrant first.
Castle: Thank you.
Beckett: For what?
Castle: For using 'irony' correctly. Ever since that Alanis Morisette song, people uses it when they actually mean 'coincidence', drives me nuts!
Beckett: Yeah, well, it must be your great grammatical influence over me.

Title: When the Bough Breaks

The title comes from a classic bit of folk poetry, first known recording appearing in 1765, which has become part of a song titled "Rock-a-bye Baby". The current most popular form of the lyrics is
Rock-a-bye baby, in the treetop,
When the wind blows, the cradle will rock,
When the bough breaks, the cradle will fall,
And down will come baby, cradle and all.
The song is said to be the first poem written on American soil. It may have its origins in political matters, as well, possibly referring to the son of England's King James II, who may have had a baby snuck into the birthing room to become heir to the throne (the child was never king, the Glorious Revolution replaced the Catholic James with the Protestant William and Mary).