I recently slept over a friends house and got dropped off at home early, I caught my dad and mom in their room?

being really weird. He was naked except for the big diaper he had on. He was bent over with his bottom in the air, My mom had on this skimpy black tight outfit, and a wooden paddle and was my dad with it.. I am so confused right now. What do I do or say to them? Why are they so weird? Is this normal at all? Please help!!