Green Peppers - NOT!

Finally, despite the cool and wet summer, my peppers are producing.  I purchased what I thought was a standard green pepper.  However, as you can tell from my picture above, that isn't what is growing. 

These peppers are thumb-sized and are pale yellow turning purple-brown.  The flesh inside is yellow.  They taste bitter with a bit of spice on the front which quickly disappears.  The flavor reminds me of regular peppers, but not quite the same.

Any ideas on what I've got?