Season 1 Episode 24-5: Guest Stars on Sam & Cat

Jennette McCurdy made a vine revealing that there would be be guest Stars Matt Bennett (Robbie Shapiro from Victorious) Liz Gillies (Jade West from Victorious) and Nathan Kress (Freddie Benson From iCarly).

This will be aired over episode 24 and 25 of the season, Sam & Cat Special. 
This is the synopsis of the episode:  When Sam meets Cat's friend Jade from Hollywood Arts, Sam and Jade become friends, leaving Cat feeling a little left out. Taking some questionable advice from Nona, Cat decides to retaliate by "stealing" a friend of Sam's — and it's Freddie Benson! As Cat tries to get cozy with Freddie, Sam finds out and goes after a friend of Cat's — Robbie Shapiro! The jealousy comes to a crashing climax at Fisherman's Wharf, where Dice has hired Sam to jump her motorcycle over a tank full of vicious man-biting tuna.



More of Jennette's Vines regarding this: