If you forum on either Roblox Talk/Off-Topic/Let's Make a Deal, you probably know about the ROBLOX Card glitch. You may have seen people raging about how they bought ROBLOX Cards with their own money. This glitch occured around 4:00 PST Aug. 16th and stopped near 4:30 PST. Aug 16th.
Here's how it all started....
Roblox was testing ROBLOX cards on the gametest. They accidentally turned the free version on for the (www) site. So when you clicked the Roblox Card button on the Builder's Club page the code was already filled in. You were allowed 20$ worth of credit on each account, then people decided to use alts and override it to their benefits.
When the admins found out this was happening they decided to turn the switch off. At this time people were scared to try the glitch because people thought they would get banned. Later on, Brighteyes announced it was an accident made by them and they would let everyone keep their credit and not do a thing.
So if you're wondering how people got the free BC and robux, this is it.