Why is it we only do this for some things but not others?
Is because there is not an exact equivalent to the name 'chapulin' in english, and is a distinctive name, so is useful to keep the word.
I guess I understand why people do this. It's obviously not wrong, because nobody can speak incorrectly. It just strikes me as a bit of a cultural misunderstanding, but that's how things are.
Chapulín have a richer meaning, can be used to name a dish, a type of insect (including some crickets), can be easily interchanged as toddler, or as 'a dishonest politic' (that jumps to another party), and is also a beloved super-antihero of a popular series for children in the mexican tv that was later photocop... parodied again in the simpsons to make fun of latino spanish speakers (bumblebee man).
There is a train of thought in linguistics that there is no such thing as an exact synonym.
http://linguistics.stackexchange.com/questions/2062/do-absol...