Definitely a 4 lettered word !   Using the word just as an opening to introducing ourselves or what we have to say is a big big downer when it comes to being effective in communication and making the person we are talking to feel valued.  Whilst it makes sense saying "it's just me" or "I just wanted to ask" may make us sound unimportant, consider it is also disrespecting the time the other person has given us with their attention or answering our call.  It adds nothing and detracts a lot, this weeks challenge.... no using "just".