You can set up multiple taunts (messages only) for multiple key binds, i.e.:
bind u "say Good kill!"
bind i "say Yes! Another point for me!"
Or, if you want to get crafty, use variables and reassigning to set up multiples, in the following style:
bind u "vstr chat00"
set chat00 "say You think you're some kinda Jedi, wavin' your hand around like that?;bind u vstr chat01"
set chat01 "say In my experience, there's no such thing as luck.;bind u vstr chat02"
set chat02 "say I have a bad feeling about this...;bind u vstr chat03"
set chat03 "say May the Force be with you...;bind u vstr chat00"
In this method, the first time you press u, you send the first message. The next time you press it, you get the next message, and so on, looping back to the first.
Do like I did -- set one key for various things to say when you get killed, another key for various things to say when scoring a kill, etc.