I think it's for charity. Actually, I'm not really sure what it's for, outside of our entertainment. But these online 'fitness models' (or whatever they want to be called now) have taken time out of their days to post these videos to raise awareness for...well. You know what, this is a scam. Apparently this was all created by some Adult Film scouting agency...but whatever...FOR CHARITY!

They're still trying to make it seem like this is a real thing. The charity isn't the only fake thing here...

https://www.facebook.com/HoldACokeWithYourBoobsChallengeOfficial/timeline

Check out this compilation video: