A intended mispelling in leet speak, originally coming from having root access to a UNIX operating system such as if it were your computer you would own it, but by means of exploiting a hole in their system, you gain full control of their system, and in essence own it, or should I say 'pwn' it. If you are a victim of such an escapade you would be considered 'pwn3d'. This has been taken out of context as you can see over the years buy wannabe "hackers" and children with nothing more to do than try to act `leet`.
"Yeah, he was running a vulnerable finger daemon and I pwn3d his ass with a simple buffer overflow"
"haha, you got pwned by that guy with 4 fingers"
"all your base are mine, i pwn you"