When a ginger (someone with red hair and freckles) becomes angry and reckless. Usually because he/she has no friends, or is picked on continuously by the brave few who would talk to them.
Calum: Hey Sarah, is Caroline on fire?
Sarah: No, that's a ginger snap.
Calum: All I did was tell her to either jump off a bridge or get some hair dye!
When a ginger or a redheadsnaps-i.e. has a sudden outburst of anger that is extremely powerful and scary. Kind of like a breaking point, except every ginger has some type of a "ginger snap" in their life. The outlet of redheaded rage.
Yesterday, that redheaded kid in our math class had his ginger snap and started beating up this other kid. It was the craziest fight I've ever seen!!!