$snick
From Scriptwiki
$snick(#,N)
Returns the Nth selected nickname in the channel listbox on channel #.
Note: If the N parameter is not specified, it returns a line containing all selected nicknames (same as $snicks.)
Example
$snick(#help.script,0) returns the total number of selected nicknames on #help.script
$snick(#help.script,1) returns the 1st selected nickname on #help.script