What did your parents, especially your mother, call your penis?
My own mother called it the “device" (appareil in French). This is not standard. Perhaps this was short for appareil genital (genital apparatus, genitalia), but I don't think she also meant the testes.
If she wanted to refer to the whole genital area, for instance for reminding me to wash, she could say the “front” (devant), as opposed to the buttocks and anal area, “behind” (derrière). Both places were collectively referred to as “the below” (le bas), as in “remember to wash below”.