Usually FanGirls have more than one saying. Here's a few cliche ones to get you started!

"WHYY" =Usually after a tragedy or something that happens to their bae or favorite character. Sometimes when a character gets between their ship.

"HELP ME"=After someone watches too much anime/show, and is now on the verge of dying.

"FOR REAL" "FR!?"= Just like "WHYY" , but now it's more a mad perspective, and will kill whoever gets in their way of their ship/armada.

"AHHH"=When something cute happens with your bae, or you read a fanfic about them. Reading fluff usually is what triggers this reaction.

"WHA!!?"=When you get confused.

"DONT GO THERE."=They usually say this by staring in your eyes. You must have said something about their fandom being dumb.

"mmhm.."=While watching the show/anime, this will happen. Knowing that this person is Kira while denying it, you still fall hopelessly..- Anyways it means you know who 'it' is even though they're lying. Heh..

"I'm literally DYING."=Sometimes used when actually dying, or when something happens that makes the person laugh or cry. It might take weeks for them to stop laughing or sobbing.

"SO CLICHE"=Use when reading or watching something that is cliche. For example, this book.

"IM DONE."=Seeing the most stupidest thing in your anime/show etc, and being done with it. It also could mean something so funny just makes you done... I'm done.
~

ACTIONS:

*Buries face in hands*= Usually goes with "WHYY". When you have became sullen over a tragedy.

*ball up into a ball.. Squeals*= when something cute happens to your ship or you read awesome character X reader fanfic.

*covers mouth with hands*= when someone dies. Even if they're not important.. They're dead.. So.. Yeah.

*buries face in pillow*=same effect with "WHYY", but instead with a pillow, that's much softer. This is easier if your hands have Cheeto dust on it.

*has hand on heart*= Not JUST USED for the pledge of allegiance, but also when you say, "IM LITERALLY DYING".

*hand on chin*=when you say "mhmm", "mm.." "Mhmmmhmhmhmhph." Etc.

*face palm*=when seeing your bae getting dumber by the second.