Get its total area in kilometers and its rank among the world's countries. Then multiply those two numbers.
For instance, the United States is ranked fourth in the world by total area with roughly 9,372,610, so the product is 37,490,440.
I'll call this product the LRP (Leaderboard Rank Product).
Now the question is: Which country has the highest LRP?
What makes this interesting is that the rank number seems to increase at a similar exponential rate that the countries' areas decrease, especially as you move further down the list.
The United States' LRP is instantly dwarfed by 5th place (in area) Brazil (42.6 million LRP) and 6th place Australia (46.15 million LRP).
As we go further down the list, we find that:
19th place Mongolia has an LRP of nearly 30 million
30th place Egypt barely exceeds 30 million
50th place Yemen exceeds 25 million
but the trend dies down by 100th place, Malawi, which only has an LRP score of 11.8 million.
Vatican City's LRP doesn't even reach 100.
I think Australia wins this one, but if I'm wrong, please correct me!
You can do this with any set of items that are objectively ranked with concrete numerical statistics. Have fun!