Wait wait, do you want a single line or a single word? If a line, then:

srand; # seed the random generator

open(FILE,"file.txt"); # put the file contents into an array
@file = <FILE>;
close(FILE);

foreach (@file) {chomp} # remove the newlines

$line = $file[rand($#file)]; # select a random line
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If a word:

srand; # seed the random generator

open(FILE,"file.txt"); # put the file contents into one big scalar
while(<FILE>) {
    $file .= <FILE>;
}
close(FILE);

$file =~ s/\r/ /g; # remove carriage returns and replace them with spa
+ces
$file =~ s/\s+/\s/g; # remove multiple consecutive spaces

@file = qw($file); # seperate the file into single words

$word = $file[rand($#file)]; # select a random word
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The code is kind of comment-laden, but they're just so you know what's what.
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When I get a little money, I buy books. If I have any left over, I buy food and clothes.
-Erasmus