backslashes in comments

My comments have backslashes before the quotation marks, like this: \”bored\”

I tried searching for a solution, but I couldn’t quite follow the one I found. http://wordpress.org/support/topic/5889?replies=28 said to use this

add_filter(‘comment_text’, ‘stripslashes’);

and to paste it in the vars.php or somewhere else. But when I pasted it in the vars.php, it messed up my site. Can someone tell me very specifically where I should put that tag?