YellowCard

Your smart phone can have a new function: Yellow Card

If there is someone who violates the rule around you, you can simply launch this app and use it as a Yellow Card for warning the person.

This great app has another function: Red Card

If you touch the screen, the app generates whistle sound. You do not have to carry whistle and colored cards any more!

There are some secret command to change it to another color. This secret command is disclosed in App Town's blog on the release day of this app.