阿姨借你女儿一用阿叔借你儿子一用
[ā yí jiè nĭ nǚ ér yī yòng ā shū jiè nĭ ér zi yī yòng]
This username humorously suggests that it's about borrowing someone else's children (daughter from aunt and son from uncle), but the actual context could be unclear or playful. It might imply a family or friendly relationship or an inside joke.