I usually don't do stuff like this, but anyway, I'd like to say what I personally would do in iOMG.
As we know, Carly and Freddie THINK Sam has a crush on Brad. They try to get them together, but when that fails, Freddie talks to her (promo scenes). Sam eventually admits that she loves Carly, but is afraid of losing her if she admits it (Insert Seddie hug here; Sam and Freddie have a weird but good friendship, IMO, but I simply can't see much romantic chemistry between them). Carly has seen and heard their talk, but they don't know that she knows.
When they get home from the lock-in, Carly is confused about her feelings and how to deal with the knowledge of Sam's crush on her. She talks to Spencer about it, and he listens and eventually asks her if she would be okay with dating a girl. Carly is about to answer, but before she can, Spencer sets something on fire again and the episode ends with a cliffhanger like iThink They Kissed.
Remember, this isn't supposed to be a realistic prediction, just a Cam shipper having some fun. That being said: