When someone comes into a classroom

When someone sneaks behind another person, so to warn the victim you yell Red Hawk.

A derogatory slang description of a sexual maneuver, which can only occur when a girl is on her period. The man, frustrated about how disgusting it is, pulls out of the bloody vagina and flips the girl over yelling, "Caw, bitch!" Finally, he whips his bloody penis across her ass, thus the red tail.