well you could do it alot of diff ways but smaller is not always better..
heres another way lmao

menu channel { 
  .Random Nick
  ..Echo ChangeNicks:{ echo -a Nick now randomly changed | rannick } 
}
alias rannick {
  var %f NICK1,NICK2,NICK3,NICK4,NICK5,NICK6,NICK7
  nick $gettok(%f,$r(1,7),44)
} 

or again i do like E\'s way also it\'s ez to read for beginners to learn from...