However, it's important to note that this phrase is often used sarcastically or humorously in Spanish-speaking cultures, and it's not meant to be offensive. It might be used to refer to a brother-in-law who is:
* Slightly overweight: The literal translation is "fat," but the term is used playfully in many cases.
* Annoying or overbearing: The phrase can be used as a playful insult to a brother-in-law who might be seen as interfering or irritating.
* A source of amusement: The phrase can be used affectionately, even if the brother-in-law is not actually overweight.
It's always best to consider the context and tone of voice when interpreting this phrase.