hey.scala

class Bippy(override val toString: String)

trait A            { implicit def lowPriority: Bippy  = new Bippy("A") }
object B extends A { implicit def highPriority: Bippy = new Bippy("B") }
object C           { implicit def highPriority: Bippy = new Bippy("C") }

object Test {
  def main(args: Array[String]): Unit = {
    import B._, C._
    println( implicitly[Bippy] ) // Prints: A
  }
}

Literate programming:

object B extends A { implicit def `the one where B introduces a better bippy`: Bippy = new Bippy("B") }