You can set custom sounds that play when a specific player logs in.

MacFIBS does not offer a direct way to add player sounds, but if you are familiar with Mac resources and ResEdit, you can easily add sounds yourself.

While MacFIBS is not running, open the MacFIBS Preferences file (in the System > Preferences folder) with ResEdit. Copy your 'snd ' resource into this file and give the resource a name that corresponds to the associated player's FIBS name. Your 'snd' resource ID should be in the range 1000 - 9999. Do not use ID's in the range 10000-11000, as these may conflict with sound resources used by MacFIBS.

Tom Hauk's MacFIBS Sound Page
www.geocities.com/Hollywood/2633/sounds.html