car⋅co⋅lep⋅tic {kahr-kuh-lep-tik}

adj, Pathology.

A disorder characterized by the sudden and uncontrollable attack of deep sleep immediately following a promise to your roadtrip buddy to stay awake the entire time.

See carcolepsy.
"I'm sorry officer, my roadtrip buddy is apparently carcoleptic and neglected his duty to keep me awake. That is why I drove through your town's annual Midnight Midget Parade. I think a few of the buggers are still lodged beneath my car."
by Ben Brandt March 4, 2009
Person who falls asleep immediately upon sitting in an automobile. Person who suffers from carcolepsy.
The bobbing head, drool and loud snoring clearly identified the person sitting in the passenger seat as a carcoleptic.
by croecko August 1, 2013