Never heard of it. Should be certain dialect of northern China by the use of 怂. I suggest you ignore it cuz in my 23 years time in China, I never heard people say it in both real life or on TV. But I can tell you the meaning of each character and words with close meaning.
坏 means "bad". Simple.
怂 means "coward"(adj). It's a fairly offensive term used often in the north. It implies a person can get cocky, bully, etc. when they face no threat, but becomes coward when real courage is needed, and you despise him.
娃 is "kid, child", "young person", or someone your age. When used here it means you don't respect this person.
Related words: 怂货. 货 is "goods", "merchandise". When using it to describe a person, it means you despise and hate him so much that you don't even see him as a person, instead, a thing. e.g. 怂货 a coward; 贱货 a person who doean't have dignity and honor.