I've always thought that "cold pizza" was an expression used mainly to refer to a boring, uninteresting person or an unexciting event whose images call to mind that of an unappetising cold pizza.
According to Ngram "cold pizza" has been used increasingly from the early 70's.
The is no clear reference on this expression (just UD mentions it) and its figurative usage may lend itself to different interpretations at times, but I've noticed that it is often used referring to breakfast:
- If you haven't had cold pizza for breakfast, you're not a musician and therefore, I'll refund your money for this book.
- You know, in law school, we used to eat cold pizza for breakfast...
It is also the name of a TV sports morning talk show in the U.S.
1) Is the expression actually used to refer to a boring, uninteresting person?
2) What are the other (if there are) figurative usages of "cold pizza"?
3) Is it mainly, as it appears, an AmE expression?
EDIT: I know that the expression comes from some eating habits of American people, my question is about the figurative usage of what a piece of cold pizza may suggest.