Bert dreams of how he and Jenny make out in the park, but the fantasy quickly collapses. She is the sister of Bert's worst enemy, Klimpen, who is always around when Bert tries to talk to Jenny. What is he going to do? Åke comes up with a studied plan.

There is a swimming lesson and Bert looks forward to spying on the girls in swimwear, but when Thora explains that the girls are spying on the boys at least as much, Bert panics. He finds a miracle diet on YouTube that will give you a super body in three days.