Little Johnny walked into his dad's bedroom one day only to catch him sitting on the side of his bed sliding a condom onto his penis in preparation of sex with his wife.
In attempt to hide his full erection with a condom on it, Johnny's father bent over as if to look under the bed.
Little Johnny asked curiously "What ya doin' dad?"
His father quickly replied, "I thought I saw a rat go underneath the bed."
To which Little Johnny replied, "What ya gonna do, fuck him?"