Moved to Forum: Original Link
Looks like code is generic. Free boxers for everyone! (thanks Scatman00 and others for confirming)
Changed to new code. (thanks Hintswen)
Update: All orders cancelled with unique 50% off code provided to those who used the free code
Code 29%OFFCHR for 29% off multiple pairs if anyone wants.. Seems generic. (thanks Mario1234)
Exploit? Nah that's just a cover for "OMG obvious price error but I demand they honour it as per the contract (insert Karen-style arguments)".