This poem must be read aloud in order for the joke to be apparent. Each symbol goes by it's name in the Unix world. I've also transcribed the verbal text of the joke beneath the joke itself.
Angle angle bang splat tick tick hash,
Caret quote back-tick dollar dollar dash,
Bang splat equal at dollar under-score,
Percent splat angle angle tilde number four,
Ampersand bracket bracket dot dot slash,
Vertical-bar curly-bracket comma comma CRASH!
Okay, someone else add some more poetry on to this one!!!