A phrase that on one hand has no meaning, but on the other hand means everything. It is often employed to express a feeling of pure joy, gayness, glee, or pride. It can also be used in awkward situations to break the ice, in helpless situation to raise morale, or simply when one is acting the fool.
The correct intonation when pronouncing this phrase, expressed in musical terms, is equivalent to that of a descending note sequence of "La So Fa" on the same octave. Particular emphasis should be placed on the first and third syllables, in which the third syllable is commonly extended. The "r" sound at the end of each "la" must be pronounced as clearly as possible in order to produce a cacophonous sound that either puts people off, or makes them believe you're an idiot.
In extreme cases where one is too excited to produce the complete phrase, exclaiming "Ah Lur, Ah Lur" is also acceptable and bears similar meanings.
A: "Hey how did the Halo match go?"
B: "Lar li Lar~"
A: "What the...."
A: (Out of nowhere) LAR LI LAR~
A: OMG I GOT THE ACHIEVEMENT!!
B: LAR LI LARRRRRR!!!!!~~~~
C: AH LURR! AH LURRR!!!!~~~
A: (Whispers) lar li lar
B: (Whispers back) lar li lar