Bring down the console with the tilde "~" key.

Effect Code
Toggle enemy God mode - aigodmode <0 or 1>
Toggle protectee God mode - aiprotectprotectee <0 or 1>
Toggle God mode - god <0 or 1>
Toggle enemy AI cannot hear you - aidisableears <0 or 1>
Toggle enemy AI cannot see you - aidisableeyes <0 or 1>
Toggle no clipping - noclip <0 or 1>