The Hitchhiker’s Guide To The Galaxy, abbreviated as HHGG or H2G2 is a film from 2006 based on the novel by Douglas Adams. Here is a very short clip:

Trillian: We have normality…
Arthur: Normality! Right! We can talk about normality until the cows come home.
Ford: What is “normal”?
Trillian: What’s “home”?
Zaphod: What are “cows”?

We can talk about XXX until the cows come home, is an expression that means regardless of how much we talk about that topic, it may never become clear. In this scene, Ford has travelled in space and time for many years, and is very disoriented. Trillian has just heard that her home planet, Earth, has been destroyed. Zaphod… well Zaphod is just self-centred, vain and, well, stupid. Oh, and he also happens to be the President of the Galaxy.