Example: Your friend is on a diet and you just bought a milkshake from your favorite resteraunt. Then you start talking about how good it is and you offer some to your friend. Your friend says "No thatnks im on a pretty hardcore diet." Then you tell him "One little sip is not going to hurt your stupid diet... Come on." and then your friend is like "Fine your right....*Tries it*... Thats good im totally gonna go get one."
Peer pressure is the influence from members of one's peer who are of or almost the same age group. Peers are those who are part of a similar social group. Most parents often worry about peer pressure because it makes their children to have weird behaviors.