Follow the leader
It’s easiest to explain this negotiation technique by switching sides to purchasing. If you know that the competition use it successfully then you should probably look into it. Relate this to a social media influencer, or to a celebrity endorsement. In trading they used to call this the ‘big swinging dick’. For example:
Elon Musk buys stock in Bitcoin and it drives up price because millions of people follow suit
Kim Kardashian wears Prada on Instagram and now everyone else wants it
It basically means that once the person at the top of a social hierarchy makes a purchase (the alpha) everyone else follows the leader. It’s why people get paid a hundred thousand dollars to post a photo in insta with a pineapple juice.
You could also use it in day-to-day negotiation is to name drop. For example if I know the football team my prospect supports, I might be able to mention that their favorite player also wears this brand of shoe.
This can take a good amount of not product knowledge but your current customer knowledge. You may also use this as an opener to build credibility by stating that the buyers competition is a current customers to create faith. For example if you were talking to Optus you may say ‘would you like to know how we saved Telstra 5% on 5G set up?’