| I can't believe this is a nodeshell. What a terrific word.
My dictionary defines schtick as "1) a show-business routine ... inserted in order to gain a laugh or draw attention to oneself; 2) one's special interest, talent, etc." Both are noun forms. The word has entered the English language from Yiddish. It can be alternately spelled shtick or even shtik; but for my money this is the best spelling.
In my circle of friends, this word has grown substantially in meaning. Recognizing that a schtick, as a comedy routine or other gag, is generally a good thing, we have adapted schtick to mean almost anything of high humorous quality or other value. Thus, for example, Steve Martin's performance in The Man With Two Brains was quite a schtick, making Mr. Martin himself quite schtickful. It is also a schtick, for instance, that it has become commonplace for eating establishments to offer free refills for your soft drinks, but it is not a schtick that hotels have universally begun charging for local phone calls.
Compare with other formations, such as schtickhead. Generally speaking, in my universe, the antonym of schtick is buckle--though things are never "buckleful," you can quite easily be a bucklehead. | 
