Hi Sasha A 'tattletale' exists as a noun (meaning someone who informs on another). For example "He was the tattletale of the class. You could never trust him to keep a secret." I would say this isn't very common, and sounds a bit old-fashioned, but then I'm a Brit and I believe this noun may be more common in American English. You can also 'tell on' someone. Which also means to inform the authorities/not keep a secret.I would say this is very common in British English. It's often, but not always, used in the context of bad behaviour by a child, so it's quite informal. For example "If you don't stop, I will go to the teacher and tell on you.' I have never heard these two phrases combined into one verb ' to tattle-tale on' - it could be a dialect form or a new emerging form of the language perhaps?

US - "tattletale" is a noun. It is someone who tells the authorities when a different person does something wrong, usually because they want the other person to get in trouble. ("John told my mom that I ate cookies before dinner. He is a huge tattletale"). It has a childish connotation; it's something that children do to each other. When an adult uses it about another adult, they're also implying that the adult who is going to the authorities is being childish. And it has a negative connotation. Calling someone a tattletale is an insult. "Tell on" or "tattle on" are the verbs (I would probably not use "tattle-tale on") . Again, they're both negative and childish, especially "tattle on."