Shareef O’Neal just revealed his heart surgery scar for the first time Wednesday … and he’s already given himself a new nickname, “Zipperboy.”

TMZ Sports broke the story … Shareef needed a heart procedure done after UCLA doctors detected an abnormality during a routine check-up.

O’Neal went under the knife on Dec. 13 … but came out of it just fine — and when he finally got a look at the scar this week, he was able to joke about it.

“My first time seeing my scar ….. #zipperboy.”

The operation doesn’t seem like it was a laughing matter though … the scar runs from the top of his chest to halfway down to his belly button!!!

The good news … Shaq told us just several days ago his son’s doing okay — and could be back on the basketball court in just a few months.