Someone

on *:JOIN:#: { 
  set %whoisnick $nick 
  set %whoischan $chan 
  whois $nick 
} 
else { 
  halt 
} 
raw *:*: { 
  msg %whoischan %whoisnick is currently on: $3- 
  unset %whoisnick 
  unset %whoischan 
}