I will explain if you will...

For twenty years, a man and his wife had sex in the dark. Finally, one night, the wife abruptly turned on the light, only to discover that her husband was banging her with a dildo instead of his penis.

"What's this?" she asked.
"This is the only way I've ever had sex with you" he replied.
"Would you care to explain?" she asked.

"Sure. As soon as you explain our three children..."