The Sure Thing (1985) on Netflix

College freshman Walter (Gib) Gibson decides to go cross country to visit his friend in California during winter break. Awaiting there is a bikini-clad babe whom his friend assures him is a "sure thing". Meanwhile, Allison, a cute (but somewhat anal retentive) girl at Gib's college has also decided to head out to Cal. to see her boyfriend during break. Gib and Allison are thrust together on a road trip from hell, and somewhere along the way, they find each other's company to be tolerable. Now, what will become of Gib's "sure thing?"