The a reaction to seeing and/or hearing ick they have. Similar to freaking out. Usually a face of disgust and you cringe.
For example Casey was icking out when she saw Jake a guy with ugly looking feet wear flip-flops to class
Getting the ick on someone so badly you will never be able to see the person the same again.
Icking out on someone to the point where you can't see the person the same anymore.