From far and wide erythrocytes
arrive displeased with their purchase.
“Trade your O2 for CO2!”
It seemed like a steal at the time.
No problem, returns are welcomed.
No proof of purchase is required.
Just gather in the atrium
then form 2 lines into the lungs.
Satisfaction is guaranteed.
It's what keeps them coming again.
Falling for the same deal again.
They would buy swampland if they could.
The customer is always right.
Nature is usually, too.
In this store no sale is final
until one day it is final.

The publication costs of this article were defrayed in part by page charge payment. Therefore, and solely to indicate this fact, this article is hereby marked “advertisement” in accordance with 18 USC section 1734.

Correspondence: Adam Possner, George Washington University, General Internal Medicine, Medical Faculty Associates, 2150 Pennsylvania Ave NW, Suite 2-105 South, Washington, DC 20037; e-mail:

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