CuCN - My username.
CuCn - Please capitalize all three letters if you're going to capitalize any.
cucn - OK, I guess.
CuC, cuc, Cu, cu, c - You're too lazy for the fourth (third, second) letter?
coppercyanide, cuprouscyanide, copper, cuprous, cuprum, cyanide - Fine, if you want to type something that's longer than the username itself <.<
cyan - Fine with me.
002 - I'm a secret agent! (Only by kim/73. It does have something to do with the username.)
0z9tu - My username on Kong. (It's a bunch of random characters.)
0z, oz, ozzy - Common abbreviations.
wizard of 0z - Yes, I have seen this plenty of times. Don't do it.
otyugh - One person on Kong uses this. It doesn't fit me at all.