Step 1: Show up uninvited. It's like a reflex. You're not really sure why you're there, but you just show up. Like clockwork.
Step 2: Find the host's secret stash of snacks
Disclaimer: Crashing parties may lead to temporary friendships, permanent awkwardness, and possibly a few hours in a holding cell for trespassing.
When the host tries to trap you on the couch, remember that the true key to escape is not to fight, but to... well, just don't. Stay. On the couch.
Subchapter 2: The Fridge Defense - An Exploration in Refrigerated Futility