1) Used in lieu of a word you can't remember, but whose meaning can be understood in context. Typically replaces a noun, but can be a verb or adjective if necessary.
2) Appended to a sentence to signify uncertainty, often in a shaky or questioning tone.
It's pouting out here! I wish I'd thought to grab my juber when I left home this morning.
That sounds like a good plan...juber.