An easy substitute and / or acommpaniment for:
Expressing disdain, indifference, shame, and / or sympathy.
Shrugging. (files under expressing indifference)
Person A: What do you have to say for yourself?!
Person B: Merf..... I'm sorry.
Person A: Merf... Today sucks
Person B: What's wrong?
Person A: What do you think of my new girlfriend?
Person B: Merf... You could do better.
Person A: My boyfriend is a jerk!
Person B: Merf, I'm so sorry. You deserve better.
Person A: You're incouragable...
Person B: Merf.
The group of kids around Oba started to mimic the cat in saying merf and it spread from there as a nonsense word that can mean anything, yet nothing.
For verification, search usenet posts back in the early 90s, and Northern Lights BBS.
Person 2: merf