My tennis balls

I have lots of tennis balls because Jean's dad plays tennis and gives me the used balls.  They are perfectly good balls and I love them.  I have some inside and some outside.  I really can't tell the difference.  For some reason Jean does not want me to bring my inside balls out or my outside balls in.  They are all tennis balls to me.  Today we were going outside and I had a tennis ball in my mouth.  Jean said, "Drop it".  I am a good boy so I dropped it but I picked it back up.  Then she said drop it again and I dropped it.  Then I quickly picked it up again.  We did this several times until Jean grabbed it so I couldn't pick it up.  Then we went outside and got and outside ball and played catch.