I walked in on my mom and stepdad banging
That's traumatizing. Are you sure that's what they're doing?
Yup. My mom's stepfather's huge cock was in my mom's cunt
You should not do that anymore. You need to give others their privacy in those moments.
Nah I'm going to watch more and maybe join in.
It's very disturbing that you want to join in with your mom and stepdad having sex as that will be considered incest, and it is not a healthy way of living. I hope you give them privacy and just apologize you have walked in on them and promise that it will not happen again.