Many people are afraid of hitchhiker's, but less afraid of helping a motorist who has run out of gas. Imagine that, to get a ride, a hitchhiker makes a suitcase out of a gasoline can, so it looks like he’s a stranded motorist rather than a hitchhiker. A sociologist would say that he was working on:

Impression management

Explanation:

Impression management can be explained as a process in which people make attempt to control or influence other people's perception about an event or object. It can also be described as how people control how they are perceived by others.

In this case, the hitchhiker was trying to change the perception of others, that is, the people, towards the hitchhiker, which prevent them from getting help whenever they need one especially at this likely situation, by making a suitcase out of a gasoline can, so that he will look like a stranded motorist, and people will not be afraid of helping him.