Luser Attitude Re-adjustment Tool
<jargon> (LART) Something large, heavy and painful, used to respond appropriately to particularly annoying lusers.
The alt.sysadmin.recovery FAQ
recommends the following LARTs.
A 2x4 works fine, but a real professional needs something a little more effective.
Unfortunately, this is a very personal thing, and no consensus has yet been reached on the group.
Everything from a simple, 7.65mm Walther (for the Bond fans only, it's not a very good gun) to a 155mm with depleted Uranium rounds has been suggested, some even going for exotic things like Thermite, nukes or flamethrowers.
For further info, look at the rec.guns home page.
alt.sysadmin.recovery FAQ (http://www.ctrl-c.liu.se/~ingvar/asr/overview.html).