AmiNetRadio (at least version 2.56) (md5sum: 03908e363c05cb14a7b2949d3cda3ce2 AmiNetRadio) contain a easter egg that activate during the AmiWest (26th & 27th Jul 2003) between 12.00-22.00.
The fullscreen message displayed during this time is "BUY OS4".
After the laugh you may find this joke a bit annoying since it block using ANR during these times.
I've developed a patch against the abovementioned AmiNetRadio 2.56 binary. You can download it from AmiNetRadio-2.56-amiwest.pch (shift-click to save it). The patch disable the date check and the message never appears. To apply, use 'spatch -oAmiNetRadio.new -pAmiNetRadio-2.56-amiwest.pch AmiNetRadio' command.
For the curious mind, here is a picture of the activated egg and disassembly of the trigger code.