«سِيدِي بَنْدَقْ مَا سَدَّقْ»

The saying describes a person who has long been kept from doing something by some hindrance. The instant an opening appears, he seizes it without a moment's pause. Here 'did not believe' means he could scarcely believe the chance had finally come, not that he doubted it.

Bunduq is an invented name, not a real or legendary figure, and it lends a mock-honorific, playful tone that gently ribs the eager person. The jab is at the speed of his pounce, not at any wrongdoing, so it usually reads as light teasing.

Say it of someone who had been held back from something and, once the obstacle lifted or the chance came, rushed straight into it, such as a person who bolts out the door the moment permission is granted. Its teasing edge depends on how it is aimed.