To boast about one’s whereabouts through posts on social media.

These posts are not amusing or relevant for others, they are only written so that people can check in from a place. The better the place the post is from, the worse the post itself can be. In fact the post can even be non existent like in “check in” statuses.
Be aware that not every check-in status is for boasting purposes. Some people check in as an invitation to others to come to the place they are so they can “spontaneously” meet. Some also feel “obliged” to inform others about their whereabouts because if they haven’t posted on social media, it hasn’t happened.

“Whenever we break up he starts pinboasting from clubs”

“We had a terrible time in Thailand, but at least we used every occasion to pinboast”