iCarlyisms are mostly words used/made up in the iCarly world. Often they are used in other Dan Schneider shows too, which makes them also part of the Schneiderverse.
Shoosh Yeah is an expression most commonly used by Sam. The phrase is said to show excitement or an agreement of something.
The "Ushe"The "ushe" (short for "the usual") is a bet that Sam and Freddie made in iFence.
It was a bet in which Sam had to finish reading the book, The Penny Treasure, in one week, and if she did succeed, then Freddie had to stick a garden hose down his pants with the water turned on to make it look like he peed his pants, and if Sam didn't read the book in one week, she had to put the hose down her pants.
Carly doesn't seem to like this bet, probably because she's seen it before, had to do it before, or is the one who has to clean up afterwards (or just because she doesn't like Sam and Freddie's bets). Freddie loses the bet at the end of the episode and pays the "ushe."
Note: This is spelled in closed captions as the yoozh.
"What The Yuck"
Chiz is a term used on Dan Schneider's shows to replace swear words (ex: true chiz, no chiz). It is spelled with one "z" as discovered by Sam's official remote application.
On iCarly and on Victorious, it is often used.
André (in Victorious) thinks chiz to be a German sausage. (The Birthweek Song and Wi-Fi in the Sky)
Crab is a word most commonly used by Sam. It was first used in iThink They Kissed, where Sam exclaimed "Holy Crab! I love this!". There was some controversy with viewers as they may have misheard it as "the same word just with a p at the end instead of a b".
"Nooooo, Sam does not say "Holy crap!" in this scene – I promise. Listen closely. She says,"Holy crab!"
The term was again used in iCan't Take It, where Sam said, "Aww, crab!" Spencer then gasps thinking she said a profanity, but Sam corrects him saying, "I said, crab".
Hob-Knocker is an offensive term first used by Wade Collins in the episode, iRocked the Vote. It has since been used by other characters in iCarly (mainly Sam). It is unknown what is meant by the term (previously thought to have an inappropriate meaning, but it has been said by Dan Schneider that it was made up and he doesn't know what it means.)
Jank is a term that describes "totally lame" according to Carly's blog on the official iCarly.com page. It is a word frequently used by almost everyone on iCarly - especially Sam. A very similar term is also used on Dan Schneider's other show Victorious - "gank".
Jungle Worms mentioned in iGo One Direction, according to Sam are scuzzy little parasites that set up camp in your guts. The symptoms are dry mouth, chills, moaning, groaning, and excessive vomiting, according to Spencer.
Nub is a term used to describe someone geeky or rude. It has been used on iCarly several times, often by Sam (mostly referring to "nerds").
It may have originated from a sketch on The Amanda Show during a Blockblister Sketch, when the salesgirl claimed that the customer asked for a movie called The Nubby Professor instead of The Nutty Professor.
Skunk bag is a term Carly uses as an insult, though Spencer does not approve of her saying because it is not ladylike. In iFind Lewbert's Lost Love Carly said, "That lying little skunk bag!" However, Carly is not the only person on iCarly to say "Skunk bag". In the same episode Freddie said "Skunk sack" before Sam corrected him, and Marta Trundel called Carly a skunk bag.
The word was first used in Dan's previous show Drake & Josh by Yooka in the episode "We're Married" and again in his show Zoey 101 in the episode entitled Chase's Girlfriend.
Suckish is the iCarly variation of saying something "sucks." It has been changed from the active verb to the passive adjective to avoid the more adult connotations of the verb.
It was first used by Nicole in the first episode of Zoey 101.