He Did His Big One

Here's a breakdown of the phrase:

"He did": Indicates that the person took action or completed something.
"His big one": Refers to a noteworthy or outstanding accomplishment.
For example, if someone put together a fantastic presentation that wowed everyone, you might say, "He did his big one with that presentation." This means that the person did an excellent job and their effort was notably impressive.

In summary, "he did his big one" is a way of highlighting someone's remarkable achievement or success in a particular endeavor.

WOWWW he did his big one... - Leah Love Island USA