Since I dislike verbs that don't change in the past tense, I was glad to learn that 'shat' has since gained some popularity and so it can, it seems, now be considered a variation of the norm. It's used in Britain, America and Australia, so it's not some local peculiarity.
So I think we should all start using it in appropriate contexts and thereby help improve the English language a little bit! :)
And here are some usage examples. I hope you enjoy them as much as I did. I found them rather refreshing on this gloomy winter day.
I was especially impressed by this particular translation.
o_0March over there, look him straight in the eye, and say, "I'm the man who shat in your boot." and then you and in the ass
Пойди к нему, посмотри в глаза, и скажи: "Это я нагадил в твой ботинок", а потом нагнуть его и как следует засадить.