But what does "sffcei" mean? <:)

It's possible that they used a Bloom filter to compactly represent the list of banned words. This would allow them to share the filter without explicitly sending the list of banned words, so you'd never see a "foul-mouthed" network packet. But it could also return false positives for random strings, like perhaps "sffcei".

http://en.wikipedia.org/wiki/Bloom_filters

Nothing. http://www.urbandictionary.com/define.php?term=sffcei

If UD doesn't have it, I'm convinced nobody has ever used the word to mean anything dirty.