It's the last time they're going to go on a fishing trip together, and it's not a good one. They need to bring some meat upstairs so they can leave the rest of the trip in the trunk. This isn't the first time that they've done this, but this time, it was totally wrong, and now they'll never do it again. He doesn't blame himself for what he did, because it was wrong, but he's also not going to blame his sister for what she did, either. He's just having a good time, and he wants to play with fire. He wants to have sex, and she wants to be with him, too. They're having sex in the pool, so he wants his sister to join them. She's already there, so she'll have sex with him after they finish grilling the meat.