I had a therapist explain it to me as "inappropriate affect".

She didn't get mad at me or yell at me or anything like that though, she helped me to see how it is just another poor coping mechanism I developed in order to survive the abuses I grew up in.

The sad thing is it can get you in trouble in some situations in current real life especially if dealing with serious situations and circumstances in relationships at home, school, work, etc.

I'm better about it now, but I still find myself there sometimes - almost like a default setting - when I find myself in stressful situations it still kicks in like it's on Auto Pilot or something.

At any rate, your therapist shouldn't be "scolding" you on this, she should be helping you learn alternative ways to deal with it!