A tan and/or sunburn on one's right arm stretching from the shoulder and fully down the hand. It is caused when the passenger in a vehicle has their window rolled down and their right arm out of it for extended periods of time. i.e; a vacation trip
similar to a trucker's tan (just reversed)
1: Jealous of my tan??
2: No way you only tanned your right arm.
1: Yea I got my passenger tan on the way to Maryland.