Grammar Point
Godan verb with 'su' ending
v5s 
suffix
suf 
出すだす

to begin ..., to start to ..., to burst into ...

after the -masu stem of a verb

Verb ます stem + だす

The auxiliary verb だす (出す) is attached to the stem of another verb to indicate that an action or state has suddenly started or begun. It often implies that something which was hidden or latent has suddenly become visible or realized.

Attach だす to the ます stem of a verb to express that the action starts or bursts forth.

It suddenly started raining.

The baby started crying.

He suddenly started running.

Everyone started laughing.

Note

だす is primarily used for actions that start suddenly or unexpectedly. While it is similar to はじめる (to begin), だす focuses more on the suddenness or the outward appearance of the action. It is often used with verbs related to weather, emotions, or physical movement.

Words: 
出すだす
Radicals of radicals