Itchy mouth
Itchy mouth has a similar meaning like big mouth. It means someone can't stop gossiping or likes to kick up a fuss. It's very common among high school students and 1st year university students.
"Hey pork pie, you need to see a doctor for your itchy mouth!"
"I'm sorry teacher, I can't control myself, but you know the root cause is the school culture?
"I'm sorry teacher, I can't control myself, but you know the root cause is the school culture?
Itchy-mouthed
A mouth that's liable to get loud and say to much at anytime.