You know what this is...it describes (among other things) the ability to know when to say certain things and when NOT to...
Please, allow me to illustrate:
a) Oldest Boy stands in driveway and looking at new small ding in his Mustang says "Well, this sucks."
b) Baby Boy is told to sit and color his picture in his preschool class instead of running around...as he sits...he says..."Well, this sucks."
Mom (in a moment of frustration) says "Fine, I guess I'll have to go get a glass of wine in order to deal with all of you arguing this evening."
Baby Boy (at school) says "We made my mom drink last night."
You can see the need for lessons in discernment for Baby Boy. All the other boys have learned it, but it's hard, having a 5 year-old at home, who listens to what his older brothers say, and copies it WORD FOR WORD.
I'm going to be working on it alot over the summer, I can just see those notes coming home from the new kindergarten teacher in the fall..."Mrs. F., I had an interesting discussion with your son today...."