Bash
Bash can have three meanings.
Bash IRL
Bash -ing: To smack the living shit out of a n00b. This can be accomplished either with one's hands and feet, or the basher may elect to use tools such as a two-by-four, a baseball bat, knuckledusters, or in extreme cases a morningstar. Being bashed is a form of being pwned IRL. Internet tough guys often threaten to bash people.
If yo diss tha niggaz, yo will get yo skinny white ass bashed. Yo have been warned, brotha.
Bash Online
A mostly lame website dedicated to hosting quotes from IRC, all of which are totally fake. Unlike bashing IRL, OL bash is totally lulz-free. See Bash.org
GNU Bourne Again Shell
bash is a shitty replacement for the Bourne shell (command interpreter) that also fails at incorporating many other features from other actually useful shells (like tcsh). Most bash implementation on Lunix chopperating systems have a whopping two (2) aliases set by default, no key binding for backward-delete-word, and no key binding for ^D. You, bright user, then realize why it's called "bash"... because it makes you want to bash your skull into the fucking desk. bash is unsuitable to have as a default shell for the superuser (root) and the next release will most likely allow your system users or daemons to drop right into root.