How to say swear words in ava like F**k and more?

I see so many people doing it on lobby

probably hacking the chat box

It's not a hack, haven't done it in a few months but it involves alt codes (alt + some numbers I forgot.)

I've tried all Alt codes and doesn't work.
like Alt + 255 that make a invisible character and Alt + 99999999
and more but still doesn't work O.o