I am guessing ego and pride will still make a guy buy the wrong size.  I can't see being in line at the pharmacy and hearing some random man ask for a size small condom.

But if you do want the perfect fit, a British company called They Fit is offering size ranging condoms and an online scale so you can see how you or your guy measure up. 

According to The Sun, each size has a code when ordering online so no one has to reveal their actual measurements.  That being said, whoever is sending out the condoms knows your size!

Click here to see the scale and determine what size you should order.