#BOFH excuse #349:

Stray Alpha Particles from memory packaging caused Hard Memory Error on Server.

#BOFH excuse #16:

somebody was calculating pi on the server

#BOFH excuse #5:

static from plastic slide rules

#BOFH excuse #153:

Big to little endian conversion error

#BOFH excuse #135:

You put the disk in upside down.

#BOFH excuse #374:

It's the InterNIC's fault.

#BOFH excuse #341:

HTTPD Error 666 : BOFH was here

#BOFH excuse #227:

Fatal error right in front of screen

#BOFH excuse #264:

Your modem doesn't speak English.

#BOFH excuse #3:

electromagnetic radiation from satellite debris