Vine Star Brittany Furlan -- The Secret to Six Million Followers Is ...

How does someone you've never heard of amass SIX MILLION followers on Vine? Allow Brittany Furlan to explain ...

Our photog spotted the Internet sensation out on Larchmont yesterday with her dad when we asked how in the world she's racked up such a massive following with her six-second vids.

We won't spoil her answer -- it's really pretty simple -- but her response made her dad super uncomfortable.