1 Slang has been defined as 'facetious figures of speech'. When used improperly, it may cause embarassment and confusion to an individual. It may even stumble those 'who have ears' that listen.Yes, prayerful consideration is needed before one lets a word utter forth from his mouth.
2 It has been said that in Nebraska (USA) a male co-worker said to another co-worker that a female co-worker was "drop-dead beautiful". However, in passing, the woman thought she heard the man say, "Drop dead, beautiful!". Sadly, the woman eventually died as a direct result of that misinterpreted slang. (*Footnote: This event occurred in 1942 but the woman did eventually die in 1997 at the age of 86).
3 Would it be appropriate to substitute the word "john" for "toilet"? Well, perhaps you can ask a man named John if HE would like to be called "Toilet". Even as true Christians, using the term "brother" or "sister" to those related to us in the faith can be disheartening ESPECIALLY to those who are the only child. In fact, Jesus was the only child. Do you see the wise counsel?
4 In conclusion, the word slang is found in the dictionary immediately after the word 'slander'. We all know who the Master Slanderer is, do we not? We can only conclude that the word 'slang' is derived from the word 'slander' and must therefore be avoided altogether lest we choose to slave for two masters.