Trashy Snake

Someone who is a back-stabber but is also trashy.Will take your wallet if left unattended.Dates your boyfriend or girlfriend behind your back.Is that one friend who has 12 different friend groups all of which contain people she hates.Won't tell you if you have pit stains,pimples,or a camel toe etc

"Did you hear Becky was secretly dating her best friend Rebeca's boyfriend?"
"Damn,I always knew Becky was a trashy snake."