L.C.L.Y. is actually, in chinese "lan si, lan yong", which means a big lousy show-off when he/she knows when he/she can't do something within his/her capability. This word is commonly used among asians or chinese people when gossiping.
It's also used to describe someones attitude whereby it also matches his/her face and personality.

Someone people turn to when they're sad who makes them feel better.