For my favorite pig sound effects, I love it when they fall into a chasm going Whaaa!!!! Also, when you defeat ’em directly or destroy their structures, I love it when they fly toward you with various screams.
Like red yoshi, I absolutely despise these micropigs surviving and laughing at us even after a big attack.
I think the pigs saying “triangle” after we defeat their brothers sounds more along the lines of “curse you”.