A replacement for "you snooze, you lose." A phrased used when someone is taking their sweet ass time smoking a cigarette, and in doing so have missed an opportunity. This is generally the result of a single smoker idly wasting the time of several non-smokers, causing the non-smokers to abandon him.
The "croak" part refers to the fact that they're eventually going to die of lung cancer anyway.
It's an intensification of "what do you want, a cookie?" which shows lack of interest when someone tells something he considers very cool or amazing, mostly while showing off whith it.
For example, you can use it when you are down and someone thinks he has to tell you just NOW how happy and overjoyed he is.
(I am sad because my love is already assigned)
Annoying person: ...and I just kissed her! She requested me to bring her home and in front of her house she asked whether I wanted to see her stamp collction -haha- and of course I said yes- damn she's so friggin' hot- and then we went in and she took off her...
You: Hey, do you want a cookie from my shut-up-and-croak-box?