Penny had actually begun to feel a little bad about the whole Songbird thing. Her intentions were never to make Annie upset. In fact, in Penny's mind, outing all these people was supposed to do the place some good. Everyone deserved to know what people were really like when they thought no one was watching. For years, Penny had watched as Annie went through life overlooked, by boys, by her parents. All because her older sister was the island's sweetheart, perfect in every way. That was why Penny as Songbird exposed her for what she really was. People needed to know the truth, no matter how much it hurt.
It wasn't that Penny had anything against Lexie Tibbits. Quite the contrary, in fact. Penny was trying to help Lexie Tibbits in the only way she knew how. David Bacchus was evil. Everyone knew as much, and Penny moreso. He was dangerous, and combined with his power of persuasion, he could be lethal. It was clear what had happened to Lexie. She had mistakenly fallen for the wrong guy, and it was costing her a lot. Penny didn't know for sure, hence why she hadn't posted it as Songbird, but she was willing to bet that jerk had taken Lexie's v-card. It wasn't all that hard to believe.
Alfie's transgression, on the other hand, well that was small potatoes in comparison. Still, she knew it would cause problems at the Tibbits house. She knew Annie would need to get away, and Penny was more than happy to provide her with sanctuary. All she needed to do was get Markl out of the tub before... "NANNY'S HERE!" At the sound of the doorbell, he had somehow hurdle jumped over Penny, who was trying to get him dry, and bolted to the door to open it. "HI NANNY!" he proclaimed happily, all his glory hanging out with a trail of water leading all the way back to the bathroom and a soaking wet Penny.