Most people are getting stuck at LVL 7 Retro, there is a way around it. What you have to do you stand at the stand where you talk to people and wait untill about 5 or 6 people come in then you have to sit people in this order:
4th Mobile phone Junkies
5th Bussiness Women
Don't worry if you don't have some of the people in line. Putting them in this order creates more combo's. Try to reserve your bench for Mobile Phone Junkies and Families. Hope I have helped.
Do this for the rest of the Retro LVL's. Do extra good and unlock a Bonus Sushi Resturant.