I'm smelling poo

When you hear something and you know somethings not right - something "fishy" Instead, you say I'm smelling poo

I hear that Bradford claimed on a birth certificate that a boy was his, but the kid looks nothing like him and blood type is different. I'm smelling poo. I think his wife Shirley put him up to signing a fraudulent birth certificate to hide the real fathers identity out of spite for the true father