This is a plural of
LP aka Let's Play. Therefore,
LP's stands for Let's Plays. LP's are when someone records a video of themselves playing a video game, then they upload it for others to watch and enjoy with them. The videos usually include commentary from the LPer aka Let's Player. Some videos also include a
small box which shows the player's face as they play, so the audience can view their reactions as they
play through the game. You can find many LP's on YouTube.
Person A: Did you watch PewDiePie's LP's of The Walking Dead? I literally cried at the end.
Person B: No, but I saw the one he did for
Heavy Rain. It was an amazing game.
Person C: Do you guys watch any of
Cry's LP's too? He just did a new LP
of The Wolf Among Us. It was pretty boss. I can't wait until the next installment comes out.