Arriving home that evening, he gave her a third degree examination.
"How old are you?" he asked.
"None of your business," replied his mother, shortly.
"Okay, then how much do you weigh?"
"That's not your business either, young man."
The boy thinks a minute then delivers his final bombshell. "Well, then, can you tell me why you and daddy got divorced?"
Shocked and appalled, Mom sends junior to bed without supper.
The next day, the kid reports his failure to his schoolmate. "I know!" says his buddy, "Just look at her driver's license in her purse. It'll tell you everything you want to know."
Later that day, Mom finds her son next to her disemboweled purse, holding her driver's license.
"Just what the heck do you think you are doing?" she yells.
"Well, you wouldn't tell me what I wanted to know," says the junior detective, "but my friend said it's all right here. See, you're 40 years old...you weigh 145 pounds...and daddy divorced you because you got an 'F' in Sex."