Mushmouth American slang
Someone who does not or is unable to express their feelings or ideas clearly.
Whenever I don't have enough sleep, I become a mushmouth.
I felt so ashamed of myself for being a mushmouth.
If I hadn't been a mushmouth, I would have been chosen for that position.
This slang dates from the mid 19th century.
To punish someone or something harshly
He's a really strict teacher, so he'll definitely lower the boom on you if you don't do your homework.