Walkabout - a period of wandering, usually in reference to Aborigines.
Walloper - one who thrashes someone.
Wally - someone who keeps making mistakes.
Wanker - one who masturbates; a person who is full of themself, egotistical.
Waxxy / wax head - a surfer.
Wedding tackle - a penis.
Westie - someone from Sydney's western suburbs, often used derogatorily to mean uneducated and/or uncultured. Also someone who acts like a westie.
What-da-ya-know - an expression of surprise; a friendly phrase used to open a conversation.
Wombat - a simple minded person.
Wog - a derogatory term for a foreigner, especially one of Mediterranean or Middle Eastern extraction.