v4 of Open Blue's Back Story has King Armando of Avelia betting his country's second largest colony in a swordfight with the greatest swordsman in the Old World. Naturally, he lost. For a skilled diplomat and peacemaker, Tempting Fate like that wasn't exactly a pretty smart thing to do.
Whateley Universe example: during the "combat finals" at Whateley Academy, Buster (super-strong brick who gets stronger and tougher the more you hit him) drew Aquerna, one of the school losers. He lost by chasing her all over the place until she found a spot where she had the advantage. Lampshade Hanging by the instructors, who pointed out that he was so much stronger than she was, all he had to do was go to the 'win spot' and type in his answers, and she wouldn't have been able to do a thing to stop him.
In Netland VII, when Taricus decides to attack the Sarin canister, thereby killing everyone except Tyberix (who has a built-in rebreather).
You Have Become Your Avatar: Storm attempts to calm down Heartless Sora Brahian... by singing Kumbaya. Unfortunately, he didn't realize that Heartless Sora Brahian dislikes singing, so he made him more angry.