The "dear enemy effect" is a phenomenon where two competing parties develop a more amicable relationship with each other than with other competitors they do not know as well. This effect can also be referred to as the "friends-and-enemies" effect or the "neighbour-stranger" effect. More colloquially, it is also called the "frenemies" effect. Essentially, when competitors are familiar with each other, they are more likely to work collaboratively and compete fairly. This can be beneficial for both parties, as they are able to maintain their competitive edge while also fostering a positive relationship. Overall, understanding and utilizing the dear enemy effect can improve outcomes in competitive situations.