It takes a number of attributes to be a good winner. Grace, decorum, and humility are all basic requisites, but more important than any of those is the desire to actually be one. No matter what your mum tells you after another Pokémon Trading Card Game defeat, the 'taking part' really isn't what counts; it's all about the winning.
And when you win, naturally, you want to celebrate. You want to rub it in your beaten opponent's face, especially if they're an older sibling. Some people quite literally want to do that: ever heard of teabagging? If you haven't, it's not as pastoral or whimsically British as it sounds.
So when you jammily pip your mate to the post in another ridiculous round of Mario Kart, by all means take your shirt off, do a wee jump and make a victory lap around the garden. Joy doesn't come along too often in this life, and you have to grasp it when it does - even if it's a bit of a tw*tty thing to do.
There's being a good winner, then, and a bad winner. But there's also being an abysmal winner - that's when you get on your hands an knees to head a football into an empty net. Video game designers know this element of base awfulness runs through many a gamer - and they've duly gave us a multitude of options to not just beat our mates, but embarrass them.
Such as the prod. Call it the touch of evil.