TV/Movie Pet Peeve

I'm not one of those people that watches movies and tv and tries to find things that are wrong, but there is one thing that I always notice and drives me crazy.

When a character is holding a cup of coffee (or other beverage) and the cup is actually empty. You can tell by the way the person holds the cup or pretends to pour the coffee. What really gets me though is when they set that cup down and it makes a distinctive empty sound. It's so obvious!

I was just watching House and noticed it a few times. It's just one of those things....

So there you have it, one of my pet peeves. Does anyone else notice this same thing?