How to get free Shake Shack burger Tuesday

You want a free Shake Shack burger? You're in a luck, but you have to act fast.

On Tuesday, Shake Shack is giving away free Shackburgers to the first 100 guests at their restaurants worldwide.

There are three participating Shake Shacks in the 6abc viewing area: 2000 Samson Street in Center City Philadelphia, 3200 Chestnut Street in University City, and 160 North Gulph Road outside the King of Prussia Mall.

This is all part of the burger chain's celebration for its 100th location.

All Shake Shacks will begin welcoming guests at 10:30 a.m.