Depending what language I'm speaking when I say it, it's "Nine thousand, nine hundred and ninety nine" or "Neuf mille neuf cent quatre-vingt-dix-neuf."
Nine thousand, nine hundred and ninety nine
Nine nine nine nine
Four nines/All the nines (refer to their being multiple nines)
Maximum damage (or something similar that doesn't actually contain numbers)
Ten thousand
Something else
Depending what language I'm speaking when I say it, it's "Nine thousand, nine hundred and ninety nine" or "Neuf mille neuf cent quatre-vingt-dix-neuf."