Speaking manner in Islam

Have you ever in the situation sitting with a friend but suddenly when her native friend coming they speak their own language that you dont understand. you become desolated, or they whispering each other while look at you ? or they speak loudly in their native language and laughing each other while looking at you ? what do you feel ?

in Islam it is not polite, Prophet PBUH said "When three of you are together, two of you must not converse privately ignoring the third till the number increases, lest the third should be grieved.

"In the presence of three people, two should not hold secret counsel, to the exclusion of the third"

so it is understood everybody love to speak with their own language, but when you have third friend who doesn't know your language so speak with common language that everybody understand.

Prophet Muhammad Pbuh told us the manner to talk. speak good or remain silent, no lying, no cursing/swearing, speak only when we have knowledge, the point of our speaking is it for truth and is it beneficial? refrain from senseless argument, if it is debate, debate in polite manner, if the debate goes to abusive word from the opponent then leave the conversation. speak with simple language, clear to understand. we should not stealing listening of other people conversation and interrupt them. we should not speak what we hear without investigation/ tabayun. we should not spread rumor that conflict others/ nameemah. we should no talk for the purpose to show superiority and put down others, we should not backbiting/ slandering people etc.