I use Bash and frequently utilize tab completion. On my FreeBSD, when there are multiple options during tab completion, the annoying console bell rings. For C programmers, it is the ‘\a’ that you included in your printf() calls when first learning C to drive others crazy.
To disable it, as root user you can run:
# sysctl hw.syscons.bell=0
hw.syscons.bel;: 1-> 0
Add that command to /etc/sysctl.conf to permanently disable it. Good riddance!