It appears you're referring to a physical description, possibly of someone you know or have observed. The phrase translates to something like "bouncing breasts and big butt of my sister's friend" in English.
If you're looking to develop a feature related to a character or avatar that has certain physical attributes, such as "podskakujace cycki i duzy tylek" which translates to "bouncing breasts and big butt," I can offer some general advice on how to approach this in a respectful and considerate manner.
For individuals with larger breasts or buttocks, finding comfortable, supportive clothing can be crucial for both physical comfort and self-esteem.