Which one is correct?
Konnichiwa, minna-san,

what should I say when I´m going out with my friends and leaving the house? さようなら, バイ or 言ってきます ?

Question

Which one is correct?
Konnichiwa, minna-san,

what should I say when I´m going out with my friends and leaving the house? さようなら, バイ or 言ってきます ?

Answer

The answer is"いってきます"
"Sayonara" sounds more polite and serious .. we don't say "sayonara" in that case. 
In Japan we don't say "bye" but "bye-bye" ☺︎