Running Gags

Carly

 * Being "prissy".
 * Not wanting to talk about "what the goat did".
 * Being claustrophobic.
 * Saying, "Please? For me?" when trying to talk Freddie into something.
 * Constantly telling Sam and Freddie to stop fighting.

Freddie

 * Having a crush on Carly (Seasons 1 and 2).
 * Being weak and nerdy.
 * Speaking random Spanish.
 * Going on about technology when no one else knows what he's talking about.

Sam

 * Eating just about everything in sight (especially meat).
 * Constantly hurting Freddie.
 * Being lazy all the time.
 * Insulting people.
 * Using her buttersock.
 * Getting Detention.

Spencer

 * Making things catch fire, even when it's ridiculous and/or impossible.
 * Shouting/Scream-talking (Note: This may go back to his character on Drake & Josh, "Crazy Steve").
 * Tasting weird things.
 * Dating strange girls that never show up again.
 * Creating strange pieces of artwork out of insane things.

Gibby

 * Often taking off his shirt (Season 1, 2 and 3)
 * Saying "GIBBEH" in a loud voice on entering a room.
 * Showing off a plastic replica of his own head.

Credits to

 * iCarly Wiki on Fandom