Fred and Justina arrived at Fred's parents' house an hour early.
Fred's mother said, "My, you're early! Did you take a shortcut?"
"Actually, yes," said Fred. "Our neighbor suggested we take the intrastate road from our house to the state border, and then pick up the interstate that runs between our state and yours. It really worked."
"That means you can visit more often!" said Fred's mom.
"Of course!" cried Fred, while Justina dug her nails in his back. A vegetarian, she didn't appreciate her mother-in-law's veal chops (rare, no less), so these annual visits were an ordeal for her.
Back on the road, she said, "If you think that next year I'm traveling an hour on the intrastate and another two hours on the interstate for a dish of veal I can't eat, you're dreaming!"
Fred reached into the back seat, then handed her a dish wrapped in foil, with a fork taped on top. It was full of vegetables in a mild sauce. Justina quieted down to eat and Fred thought, "Thank you, Lord."
Remember: inter- = prefix that means "between" or "among;" intra- = prefix that means "within."
1) "My mother had her head examined," said Mrs. Pringle to Mrs. Prescott, "and it turns out she needs an (inter-/intra-) cranial adjustment."
2) Marie was so good at (inter-/intra-) personal relationships that she was dating seven men at one time.
1) intra-cranial (Mrs. Prescott said, "Maybe she should just bang her head against the wall, ha ha!" Quite the comic, Mrs. Prescott.)
2) inter-personal (Say, Marie, how about running for office?)