Virtual Pet Game (Using the Bathroom)

Hello,

I am creating a virtual pet game and am unable to apply a few concepts (other questions have been posted as well). Currently I am struggling to combine both the DateTime method as well as Random to achieve my desired goal. In this case, I would like to have my character leave (poop) for the player to clean every 3-5 (Random) hours. The player must then click a button to clean the screen (Reset character location? I am unsure of how to apply this action). This concept seems relatively simplistic - though I am new to Unity (though not C#) and am on a press for time.

Additionally, I would like the (poop) to decrease the character's happiness if it is not cleaned fast enough. Currently I have:

TimeSpan ts = getTimeSpan();

     _hunger -= (int)(ts.TotalHours * 4);
     if (_hunger < 0)
         _hunger = 0;
     if (_hunger > 100)
         _hunger = 100;

     _happiness -= (int)(ts.TotalHours * 7);
     if (_happiness < 0)
         _happiness = 0;
     if (_happiness > 100)
         _happiness = 100;

     _discipline -= (int)((100 - happiness) * (ts.TotalHours / 10));
     if (_discipline < 0)
         _discipline = 0;
     if (_discipline > 100)
         _discipline = 100;

Though I am not sure as to how I can apply the aforementioned (poop / happiness). Any help would be appreciated.