A QA engineer walks into a bar, and orders a beer.
Then he orders 0 beers.
Then he orders 99999999999 beers.
Then he orders an ahzuzydhu.
Then he orders nothing.
Then he orders -1 beers.
Thrn he orders NULL.
Thrn he orders jzuzuj beers.
Then he orders a "<script>giveMeYourCreditCard()</script>"
Finally, he leaves without paying, comes back and asks for the tab.

Heard this one a while ago and wanted to share it here 🙃