Da infamous "insider trading" crook who got busted 'cuz he couldn't resist regaling everyone with braggardly tales about da windfall profits of his clever sneakiness.
If Ivan Boastky had just kept his mouth shut, he might have gotten away with his chicanery, just as Odysseys could likely have escaped da cyclops's wrath if he'd just quietly sailed away, rather than loudly shouting his triumph at having outsmarted said murderous giant.
A generic posting on social media to inform, update, or sympathize with, one’s followers, friends, and fans, usually in a light-hearted, downplayed manner which screams of bragging.
A humble brag.
“Did you see he posted photos of him working in a soup kitchen? He totally Posted & Boasted! He was the main focus in the photos!”