Do you want to
1) say "Hello Nick1, Nick2, Nick3" or
2) greet each nick separately?
And do you want to
a) greet *every* nick or
b) select some nicks to greet in the nicklist (e.g. your friends) and greet only selected nicknames?
Note that while 1) may "only" annoy the users ("mass-highlight" usually isn't well received) 2) is even worse as it can be rated flood. Both may result in a kick or a ban...depending on how large the channel is and how relaxed its rules/OPs are.