To avoid doing something due to fear or lack of courage.
wimp out
To explode or burst suddenly, to become very angry and express it loudly. (real explosion as well )
Blow up
To eat excessively or greedily, usually on unhealthy food.
pig out
To lose focus or concentration, to become unaware of one's surroundings.
zone out
To become extremely anxious, scared, or agitated.
freak out
To become emotional or tearful, to have difficulty speaking due to strong emotions. ( difficulty to breathe due to obstruction)
choke up
To react strongly and unexpectedly, usually with anger or excitement.
flip out
To become detached from reality or lose concentration, to daydream or become absent-minded.
Space out
To decide not to do something because of fear or cowardice.
chicken out
To fall asleep unintentionally, especially when sitting or standing.
nod off