Julie hates Jake, one of the sales personnel who works in her department. Because Julie avoids Jake like the plague, Jake can be considered an (appetitive/adversive/aversive) stimulus.

A stimulus can be appetitive, if we seek it out, or aversive if we are trying to avoid it. For example, a burger is an appetitive stimulus when we are hungry, while burning our hand on a stove is an aversive stimulus that we avoid.