A combination of mother x son and daughter x father. The four family members will coordinate their breathing and challenge each other to ejaculate and reach orgasm at the same time! The margin of error is up to 5 seconds! Titty fucking and blowjobs will also earn you a prize for successful simultaneous orgasms! Continuous vaginal ejaculations while competing for the same timing! If mother and daughter get pregnant at the same time, the sense of guilt will double! The excitement will also double! Will simultaneous ejaculation and creampie without margin of error be successful!?