While reading a book I stumbled upon the following sentence:
He was too young to call it quits.
I can perfectly understand the gist, he was too young to be done with something, but what leaves me a bit baffled is the structure of call it quits. I am familiar with the phrase call it a day, for example, but never encountered a verb instead of a noun before. Why is it constructed this way? Are there other examples of call it <verb>?