A popular alternative for saying everything is okay. Equivalent to "no worries".
"Rainbow" is often used as a substitute for people with iOS5 who do not have access to the rainbow emoji.
Person 1: "Aye that pikunz is chattin shit about u".
Person 2: "It's all rainbowfam"
A well known phrase that essentially means the same thing as "every giraffe will find their scarf", and "every triceratops will find their berry bush".
Ted: Well you know what they say, Jim. Every unicorn will find its rainbow.
Jim: What the fuck does that even mean, Jim?