It's a very unclear statement. Maybe 'bro' and'sis' are just casual terms for friends or siblings. 'Baby' could be referring to an actual baby or perhaps a term of endearment in some context. And 'unexpected' and 'hot' might describe some sort of intense or sudden situation, but without more context it's hard to be precise.
If we correct the misspelling to 'unexpected', perhaps it could mean a story about a brother and sister having an unexpected situation related to a baby. But this is just speculation based on trying to make sense of the rather unclear phrase.