As Brenda was up against the pool wall pleading with Tina to get her bikini back her brother had found the Chronivac and after looking out the window had seen who he though was his sister being thrown into the pool. Unfortunately for Brenda when she had changed herself she had changed this reality and her brother remembered all the arguments they had growing up as if she had been picking on him.
So when Mark had seen the Chronivac and got an idea of what it could do he had decided to pay his sister back for all she had put him throw growing up.
After Mark had seen his sister get thrown into the pool and the boys enter the yard he went back to the Chronivac and started making some changes.
The first thing Mark did was to call up the stats of all the teens at the party and then maxed out there libidos before hitting enter and going back to the window to see the fun.
When Mark had hit enter things changed in the yard with Brenda having pushed her self away from the pool wall not hiding herself any longer. All the teens started to pair off with one jumping into the pool after he had seen the nude Brenda, when he came up from the dive he grabbed Brenda and started making out.