When you get your septic serviced and save the cumwad at the end of the flush, and impregnate your wife through a fingerbang with the other mans seed.
"She can't get me with child support, I'mjust the steptic father."
When servicing your septic.. and you retrieve the last cumwad deposit in the tank, introduce it while fingerblasting your next partner resulting a pregnancy.
Noun:
Steptic-Father
Her: "babe, I'm pregnant!"
You: "impossible, I'm sterile."