A sub-form of lol. The scheme of how
lolzzz was born is:
lol (laugh out loud) ->
lols (plural form of a loud laugh) -> lolz (cooler way of the same) ->
lolzz (supposedly even more cooler) -> lolzzz.
Lolzzz is usually written, not spoken, but a common pronouncement is
'lol' + a long 'z' getting lower and quieter (like a landing jet plane). It can also be pronounced 'lol-z' with a very abrupt Z.
Lolzzz can refer both to something very funny or something not really funny.
A: My boss recently bought a new PC and bragged about it all day until it showed a
BSOD and wouldn't restart anymore.
B:
Lolzzz!
A:
My neighbour's cat yesterday saw a speeding truck and got scared half to death, ran up a tree and didn't come down until the next morning, isn't it funny?
B: Lolzzz. Poor kitty.