Santana / Lyle Situation
Ok, for Christ sake, Tiffany and Lauren need to leave the Santana / Lyle situation alone. Whether she did cheat on Lyle or not it is hard to tell when a girl gets all defensive like that - can't tell if it is true shock (that you would think she could possibly cheat), or they are trying to flip it on you to deflect what they did wrong. Personally, I wouldn't bet against the fact that she cheated on him. I also could see it being during those first days (to week) when Lyle got to the house at the beginning of season 4, and he and Santana were 'broke-up'.
Tiffany is way too involved in everyone else's lives. It isn't her business; never is. But she can't help herself. Same with Lauren - she's just a mini (well - figuratively) version of nosy ass Tiffany.