With an implication of shouting, say

INCAPS

Think of how you might write a word to emphasize it in a text message, then consider the abbreviation for "caps lock."

This clue plays on the phrase "in caps," which is short for "in capital letters"—something you’d do when shouting in text. The word "implication" hints at wrapping those caps inside another word, so you take "CAPS" and place it "in" something, forming "INCAPS." The "say" suggests it’s a casual or common way to express the idea, reinforcing the abbreviation.