YOU SAID:

when you think you sleep with her dad but its her grandpa

INTO JAPANESE

あなたが彼女のお父さんと寝ていると思うとき、彼女のおじいちゃん

BACK INTO ENGLISH

When you think you're sleeping with her father, her grandfather

INTO JAPANESE

あなたが彼女の父親と寝ていると思うとき、彼女の祖父は

BACK INTO ENGLISH

When you think you're sleeping with her father, her grandfather