As you all know, Hungry Jacks have Large Frozen Cokes for $1
You might also know they have Extra Large frozen Cokes for $2
A Large is approx 600ml* and an Extra large is approx 1000ml* (BTW way, I should point out that this is not displayed anywhere. Its up to you to find out. I went to the effort of measuring it myself, after finishing my XL, still being thirsty, and wondering if 2 Large cups would have been more volume.)
So if a Large is significantly smaller than your stomach's peak expandable volume (ie, you want an Extra Large), instead of getting an Extra Large for $2, get two Larges (aka a Slightly Extra Largerer) for the same price and receive approx 200ml* extra of sub-zero sweetened beverage, for free.
Thats 20% extra for free, a massive saving of 40c.
For visualisation, thats just enough extra frozen coke to cover the face of a baby.
*actual volumes may vary depending on how thrillseeking your HJ attendant is. Do they play conservative and fill below the lip of the cup? Or are they an adrenaline junkie that likes to see how full they can fill it without spilling it.
I don't really think this is a deal…
More like basic maths applied.
But great description haha