The unpleasant emotional effects resulting from visiting a large city, and then returning to rural or suburban life.
Side effects often include depression, boredom, and general life-reevaluation.
Especially prevalent when visiting friends who have moved into the city for jobs or school, in result making you feel like you are doing nothing with your life.
Sally: "Hey! Welcome back! You want to get drinks tonight?"
Jack: "Nah.. I think I need to go home and rethink my life. NYC gave me a really bad City Hangover."
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Lucy: "I think I'm having a city hangover. I visited Caroline last week in the city and she's got all her shit together, and I'm stuck here in this ol' town. I feel so feeble."