Nugget Arbitrage

Went to McDonalds tonight after a lengthy RockBand and Pokerstars session and saw something on the menu that was absolutely baffling. A 4pc nugget is $1 on the extra value meal. A 10pc nugget is $3.49. OK, that's already messed up.

Noting this, I thought maybe the 20pc is priced in a non-arbitrageable fashion. However, there was no 20pc nugget to be found on the menu

Nevertheless, I tried to order a 20pc. Dude says they only have 10pc nuggets so it's 2 of these for $6.98 + tax.

I'm like f that noise jack. "OK, can I have 5 orders of the 4pc nuggets, please?"

"Your total is $5.23, sir, anything else?"

"That's OK, thank you."

I don't think dude realized what had just happened, but he likely will after a few more people do the same thing...

Pretty sure pricing is this way at pretty much every McDonalds in America.