Oh thanks! I was pretty scared tho xD I just wanted to clear that 'cause I don't want to be reported by saying things "I" shouldn't say in-game just because someone has my chars control xD Anyways, thanksThis is indeed a bug, no worries!! It sometimes occurs where other people will be typing under your user without knowing it, or they'll be able to control your character's movements. The simple solution is logging out and logging back in~
Such a bug Bloo described does exist, however I don't believe that is what happened here.
There are a few keyboard tricks some users (even myself admittedly) use in chat and bios and such. These tricks can be used to make a character of another person appear to say something when the original player didn't write it, and another user comes up when the character's name in chat is clicked as you had described.
This is done with ctrl+J and/or ctrl+M, which skips a line in chat and allows a user to type two lines without using enter, which evidently can be used to "pretend" someone else said something by typing your character's name in chat and afterward whatever they want to say. So for example, someone uses ctrl+J (or M) to skip a line to below their name in chat, then they type <Khumba> and any text they want afterward, in the end making it look like real chat as if a character's original player said it themselves.
I do believe this kind of behavior with these keyboard tricks is highly discouraged as it just causes trouble and mostly confusion, sometimes resulting in someone being banned for what their character said when it wasn't really them who said it but were blamed for the crime they didn't commit.
Hope this cleared things up for you.