Inspired by someone's comments on whether the Big Mac burgers
shrink during the $2 promotion, I bought 3 Big Mac's yesterday
night. 
I put the 3 burgers side by side and compared them. Burger 1 and 2
had no noticeable difference, but the bun size of burger 3 was
definitely smaller.
Next I lifted the bun and inspected the size of the meat patties, I
found that the meat patties of 3 burgers were different!
The meat patty of burger 1 is approximately 7mm thick and 69mm in
diameter.
The meat patty of burger 2 is roughly 8mm thick and 75mm in
diameter.
The meat patty of burger 3 is roughly 6mm thick and 70mm in
diameter.
I havent bought the Big mac during the non-promotional period, but
will do so later this week when the promotion ends.
