Two sons

Two men sank into adjacent train seats after a long day in the city. One asked the other, “Your son go back to college yet?”
“Two days ago.”
“Hmm. Mine’s a senior this year, so it’s almost over. In May, he’ll be an engineer. What’s your boy going to be when he gets out of college?”
“At the rate he’s going, I’d say he’ll be about thirty.”
“No, I mean what’s he taking in college?”
“He’s taking every penny I make.”
“Doesn’t he burn the midnight oil enough?”
“He doesn’t get in early enough to burn the midnight oil.”
“Well, has sending him to college done anything at all?”
“Sure has! It’s totally cured his mother of bragging about him!”