For the complete The Last of Us: Left Behind experience, read Prima's free walkthrough.
This chapter is another flashback to Ellie and Riley. Jump on the carousel and go for a ride. When you're all done, Riley will give Ellie the pun book. You can press the triangle button to tell a joke. Do this about a dozen times until you can't tell any more jokes. This counts as an Optional Conversation. When you're done, run over to the photo booth near the carousel. You get the option to interact with it; doing so will give you the final Optional Conversation of the Left Behind DLC, unlocking the bronze BFFs Trophy. For some reason, if the trophy doesn't unlock, go to the chapter select menu and use our guide to make sure you have them all.
When you're done in the photo booth, head into a restaurant next to the carousel where you told Riley the jokes. Inside and on the counter you'll find the Kitchen Note. Head up the escalator and into Raja's Arcade where you can earn two trophies. The first is in the back left corner at the Jak X Combat Racing machine. Simply interact with it and you will unlock the bronze Nobody's Perfect Trophy. In the same arcade, on the right side of the store, there's another machine you can interact with. Play the game and follow the on-screen prompts to defeat Black Fang without getting hit, earning the bronze Angle Knives Trophy.
Head down the hallway, ducking under the debris and turning right at the mannequins. Go through the double doors to a room with more mannequins. Head to the back left and through another set of double doors. After the cut scene, you enter a water fight with Riley. Just play around for the first part, but once you count to five, you need to shoot her before she shoots you. Press R2 to use Listen Mode, making it much easier to find her. This is a best out of three, and you need to defeat her twice in order to unlock the bronze Skillz Trophy.
If you're curious about the kiss, this is the point you'll find it. We won't spoil the story for you. Just enjoy the cut scene and ending to the Fun and Games chapter.