6. Conor McGregor
McGregor’s second inclusion on this list was for a much darker reason than the first. The Irishman was in a bar in Dublin when he decided to buy a round of his own whiskey brand for all of the patrons. However, one older gentleman rejected the free shot. When McGregor pressed the issue, the older man told him that he could ‘keep his whiskey.’ ‘The Notorious’ didn’t appreciate this.

His immediate reaction was to punch the man in the face. In fairness, the fifty-something-year-old took the blow very well. Needless to say, the Irishman faced charges and received a fine for his assault. But it also damaged his reputation because it was such a disgraceful action. As tantrums go, this one left a very nasty taste. Later, McGregor issued a groveling response on ESPN.