It's mostly because of the accent at times and also the speed, while talking. Similar to how English speakers say 'gonna' instead of 'going to' when speaking quickly, both these phrases change during speaking. It is acceptable in speech(as long as the other person understands you) but it is incorrect in writing. You would write 'did you' or 'do you like' but you can say it like 'joo' or 'dij'. Good question!