Daymond John is mourning the loss of his childhood friend Irv Gotti, like countless others in the music industry — and believes his late friend would have had a hearty LOL at 50 Cent‘s “tribute.”

TMZ Hip Hop caught up with the legendary Shark as he pumped himself with stem cell therapy at a research center in Costa Rica — the type of treatment he wishes Irv would’ve adopted.

Dozens of celebrities sent their condolences in the wake of Irv’s death — including 50 Cent in a half-tribute, half-backhanded fashion … “smoking on Irv pack” with a “God Bless ’em” that felt somewhat sincere.

Despite Irv and 50’s complicated history, Daymond believes Irv would have gotten a kick out of 50’s post … something The Breakfast Club’s DJ Envy can understand.

Daymond admits their Queens neighborhoods were rough growing up, but bred tough skin … not to mention how Irv and his record label infamously beat a federal money-laundering case!!!

Irv’s official cause of death hasn’t been revealed but Daymond tells us Irv confirmed he suffered a stroke during their final call last month … and the Murder Inc. exec was missing the vigor he’s known him to have throughout their lifelong friendship.

DayJ recalls, Irv and music video pioneer Hype Williams all got their start sitting on the sidelines of the artist side of the music industry … but went on to make their mark in pop culture.

The good memories include hanging out on Kanye West‘s “Gold Digger” video shoot with Jamie Foxx, Pharrell … and the time Irv told a then-unknown Pitbull to ditch the “keep it real” approach to his music.

And wouldn’t you know it, Mr. Worldwide went on to become a Diamond-selling artist!!!

Irv was only 54.