is it okay to slap someone on the butt if it is unwanted

Assault is defined in Iowa Code Section 708.1 (2011).  Assault is defined as: 1. Any act which is intended to cause pain or injury to, or which is intended to result in physical contact which will be insulting or offensive to another, coupled with the apparent ability to execute the act. 2. Any act which is intended to place another in fear of immediate physical contact which will be painful, injurious, insulting, or offensive, coupled with the apparent ability to execute the act. 3.  Intentionally points a firearm toward another, or displays in a threatening manner any dangerous weapon toward another. The code also indicates that an assault may not be involved if the participants in sports, social or other activities (not criminal) and the act is reasonably foreseeable in such sport or activity.  Also the code states that a school employee breaking up a fight or struggle does not conduct an assault. For the full code view http://www.legis.state.ia.us/IowaLaw.html Basically it is an assault to intentionally touch another person in an insulting or offensive way.