Leet speak for computer. Most comonly used because of the large number of "0's" which can be replaced with "0's." It can be stacked with other leet speak to make you look like a moron. Also can be used to replace the word boxer (underwear and combat).
i g0ts a shiney r0x0r b0x0r - I have a fine new computer.
my b0x0r is broked - My Computer is malfunctioning.
I am a boxor - I am a boxer