*is reminded of Demetri Martin*
What if the cup was half-filled with babies blood. What would you say then? That, of course depends if it's coming from or going to a baby. Because if it's coming from one then you got to say it's half-empty.
...I forgot the rest of the joke.
*is reminded by Bill Bailey*
People come up to me and say "Bill, are you an optimist?", and I say "I hope so! Eh? See what I did there?".
They say "Is the cup half-full or half-empty?", I say "Dunno, depends what's in the cup. Is it liquid? Maybe gravel? Is it beetroot, prawns, or maybe blood? Is it used in a sacrificial context?", and they say "It's alright, we'll ask someone else...".