A Chinese word, meaning 'not at all', 'yeah', or 'wow'.
A recent IM conversation:
QZ: FYI, you can download the newest version of purifyplus. The new version works fine with VS2005
Cd: thanks for the info, I'll do that
QZ: you are welcome lar
Cd: what is lar?
QZ: means nothing, just a chinese word, like not at all, yeah, wow