If you are an area where it is car washing weather, this is perfect. Find a place to do a car wash, the trick is, PRE SELL! Have your kids pre sell your tickets so no matter if the cars come or not with their tickets, you still get the money.  Yes do the car wash and take people who want to pay then.  As a small gym, we made in one day about $600 dollars with presale (the kids had two weeks to sell the tickets before the actual car wash).  We did the car  from 9am-2pm, we rotated the kids.  We had each kid sell at least ten tickets each and some sold double and tripple.