Cryptology

[Ein]

My friend gave me a code to crack. He's offering 100$ to the first person to crack it. I don't expect him to pay, but I want to see the look on his face. It's a single letter substitution code, and I don't think he's smart enough to try anything too involved. Then again it may be a load of crap, but I doubt it. Any help directly and/or decryption programs for such a code would be appreciated.

plowpn bqn fuul kgcuuwf fzqfgop zqw oqw owb zirl wn lgrwl buuconac nwg sr

Have at you.