The fact is, your code works fine, unless owo.txt is empty, and opening it like

open (OWO, "+>$owo") or die $!;
#in read-write mode seems to clear it

#this line made it work fine for me... (in linux anyway)
open (OWO, $owo) or die $!;
[download]

you might also want to do

chomp(@ary = <OWO>);
[download]

to get rid of trailing newlines... up to you...

if you do care about order from the file, you the suggestions others have posted.

                - Ant