

Mama suggests building a clubhouse exclusively for girls, and Papa adds to the idea by using an old climbing tree. Sister disagrees, but says that she can tear the boys limb from limb.

As Papa and Sister head out the front door, Mama tells them both that while the boys are being unfair, girls act that way too, and adds that Sister can't make cubs want to play with her. She tells Papa how the boys aren't being fair, to which he agrees and decides to take Sister to the Bear Country Boys Club to make them let Sister join or he would destroy the clubhouse. Angered at her behavior, the boys put out a sign that says "Bear Country Boys Club: NO GIRLS ALLOWED" out front and they let up the drawbridge. She greets them, then does her celebration dance. Sister then eyes a nearby thicket and goes there to find Brother and several other boy cubs on Berrybush Island at Frog Pond building a clubhouse. She looked at the dirt ring where they played marbles, and then went to look at the baseball field. She went to look at the tree she, Brother, and his friends climbed. On the third day, Sister wonders once more where the cubs went. The next day, Brother was not around, and Sister passed the time by having a tea party with her stuffed animals and reading books. She passed the time picking flowers and jumping rope with butterflies. One day, Sister went out to look for Brother and his playmates, but they were nowhere to be seen. Mama becomes worried that Sister was being a bad sport, as she celebrates every victory she got by cheering and doing cartwheels, leaving the boys angered. Mama and Papa later watch a group of boys play baseball with Sister. However, when Sister got older, she could outrun Brother and his friends, climb trees higher than them, and knock all of their marbles out of the game. She slowed the boys down while they were running, she couldn't climb a tree as high as them, and while playing marbles, the one Sister prepares to launch slips out of her hand.

When Sister was a young cub, she always tagged along with Brother and her friends. Mama and Papa teach both the boys and Sister that being a sore loser, as well as a sore winner, is never a good thing. In retaliation, Brother and his friends create a club that prevents girls from joining.

Eventually, Sister outperforms the boys in everything they do and goes as far as gloating about her victories. Brother, Cousin Freddy, and their friend get sick of Sister tagging along with them every time they played games.
