On your WordPress installation, you can enable or disable the conversion of certain text combination in post content or comment text into certain images called as Smilies. There is a setting under the WordPress admin => Settings Panel => Writing Settings => Formatting Section => Convert emoticons like ‘:-)’ and ‘:-P’ to graphics on display
In case you want to disable the Smilies, you can unchecked this box and keep it checked in case you wish to use the Smilies formatting feature.