This might come in some kind of quiz. So I’m posting it.
“What did Mozilla Foundation do to celebrate Firefox’s 50 millionth download?”

How obvious. They issued COINS. Just like any normal person would, of course.

Here’s a summarized version of the article from BBC:

Firefox, the open source web browser, has been downloaded 50 million times since its official launch in November. To celebrate, the Mozilla Foundation, which led its development, is giving away commemorative coins to people who have done the best job promoting it. The 50 coins were specially designed by one of the Foundation’s volunteers.

Firefox is Microsoft Internet Explorer’s (IE) main rival. Many like it because it is easily customised, while others like its tabbed browsing. This means that instead of opening a new browser window for each page a user wants, it opens a new tab in the same single page. Although Firefox has been downloaded 50 million times, this does not necessarily mean it has the same number of individual users. IE still has a grip on more than 86% of the browser market, according to web analytics company OneStat.com. But Firefox has clearly gained ground on IE. It has so far not had as many security problems as IE, and when there has been a problem, it has taken less time to fix because it is an open source piece of software. This means that anyone with the right skills can access and modify the code. It also means people are free to adapt the software’s core code to create other innovative features, such as add-ons, RSS news feed readers, or extensions to the program.

The coins were designed by volunteer Jamey Bojé