What is the origin of the term "Crystal Ball Condition"?

Question

Given $p>0$ and a family of random variables $\{X_{n}\}$, the uniform integrability of $\{|X_{n}|^{p}\}$ follows from the existence of a $\delta>0$ such that $$ \sup_{n} E(|X_{n}|^{p+\delta})<\infty. $$ This is called the "Crystal Ball Condition" (see for example Resnick, A Probability Path, Section 6.5.1). What is the origin of the term?