Some athletes get called out for leaving poor tips. Boxer Adrien Broner didn't get called out about stiffing a server, but he did feel the need to tell the world that he didn't tip on a $24 bill.
There could be some reasoning behind the "Or Nah" comment. The service could have been poor or something along those lines. He may have tipped in cash, although he probably wouldn't have written "#Shuutuup" in the caption if that was the case.
Some fans may not like the fact that he didn't leave a tip—and then "bragged" about it on Instagram. After all, Broner isn't exactly hurting for money.