A kid approaches me with his morning work, looking exhausted:

Me: “What’s wrong, bud?”
Kid: “I’m jet lagged.”
Me: “Ohhh, did you go somewhere good over break?”
Kid: “Yeah. Boston.”
Me: “Hmm, ok so Boston is in our time zone. Also it’s a pretty short flight.”
Kid: “We drove.”
Me: “Ok, so basically, you’re just tired.”
Kid: “I guess.”
Me: “Jet-lag involves being on a plane. And changing time zones.”
Kid: “Got it.”

Another kid approaches, sees his tired friend, and asks, “What’s wrong, man?”

Kid: “I’m jet-lagged.”