When you are in a crowded tourist attraction and you walk up to someone random (they should be the same age, works best with middle to high schoolers) and act like you have been friends with them forever. Then see waht they say do not laugh BE TOTALLY SERIOUS YOU CANNOT BRAKE CHARACTER
Just go as long as you can talking with them and then leave.
You: Kevin!! Hey whats up???
Person: My name is Sam....
You: Nahhh did you get a haircut Kev, hows California. I havent talked to you in like a year!
Person: No really I am Sam from Ohio
You: Keving your not funny.. dont you remember me? It's me _____
Person: I think you have me mistaken...
You: Ohh you said you were from Ohio.... Kevin is from California. You look so much like him
Your Friend: Yeah you are like Kevin's twin or something!
You: Kay Bye Kevin See you around!
Friend: Were you just Kevin-ing
You: Yeah I totally got him!