The "raspberry" sound that you make with your mouth. There's really no way to spell it so this is how its symbolized.

(noun) A successful type of theft which results in an acceptable, impressive and rewarding payday for the protagonist.

Three squigglies following each other can mean many things. It is similar to meep, as it can mean many things, usually positive or neutral things like: Hello, yes, maybe, agreed, or it can just be used at random to fill silent chat rooms. It is also used to repeat what someone said earlier without being repetitive.
Do not attempt to pronounce in real life.