Me in multiplayer with my bro: "Hey mate, welcome. Let's go exploring, just jump in that truck over there and follow me'
Kev: "Err, Poon, why is my face melting and what's all this glowing stuff in the boot?"
It would be ace to have a striped / hazardous material option for the colour gun. Whilst watching my brother cook with no hazmat suit inside a truck is very entertaining, I like the idea of marked trucks and walls to show vehicle and places that contain hazardous stuff.