An old married couple have just watched a documentary program about what happens to elderly people enduring a long and difficult decline towards death. 

Well, that makes you think, doesnt it dear? he says. 

Well what are you thinking? she asks. 

He sighs. Promise me that if ever I am dependent upon a machine and only live on fluids that you will take the necessary action. Im sure you know what I mean. 

Yes dear, she says.

 Then she switches off the TV and pours his beer down the sink.