Answer
For $\frac{0}{-3}$, you can give your negative three friends each zero cookies from your total stash of zero cookies.
For $\frac{-3}{0}$, you can give your nonexistent friends an undefined amount of cookies from your -3 cookies.
Work Step by Step
$\frac{a}{b} = c$ is another way of saying, if you have $a$ items and you want to split it into $b$ groups, each of the $b$ groups will have $c$ items.