The "Thwup" originated in the Cats movie and was first preformed by John Partridge playing Rum Tum Tugger. It occured twice in the movie (If I remember right) and occured when he got peeved. The first time it occured was when his song was interupted by Grizabella's entrance. The second time was shortly after the JellicleBall, I think.
The "Thwup" is a simple movement where Tugger takes his mane and fluffs it outwards while glaring at the culprit of his annoyance. Well now I use the "Thwup" to portray my annoyance as well. It invovles no physical contact with the one you are "Thwuping" and I often use it just to scare someone!
If you are insulted by my "Thwuping" you for various reasons don't hesitate to E-mail me and speak your mind. I have a mind of my own and enjoy sharing it. ~eg~