Ok, I kept my mouth shut.

I went to DDs for a combined b-day party for her, her son, and her daughter. The youngest boy just turned 2 and I he is really something!! I know terrible twos, I have three children of my own, but he's a little tyrant and I don't see DD or her DH putting any limits on his behavior or correction. If he doesn't get what he wants he screams and carries on. Like at Christmas when I was there he wanted the necklace that my GD gave me and when I said no he went into a screaming fit.
Anyway, we were sitting at the table having pizza and the 4 year old had just gotten up from a nap so he wasn't eating yet, just sitting there on mommy's lap and waking up. The 2 year old took the 4 year old's plate of pizza. I moved it back in front of the 4 year old. The 2 year old got upset and moved it back in front of him (he wasn't eating either of them). I moved it back and said, "That is Bobby's pizza." The 2 year old moved the plate back next to his, looked directly at me and in a very slow, low, very deliberate (and really quite mean) voice said, "Mine. Mine." And then "MINE".
OMG!!! I felt like I was just totally told off by a 2 year old! And I was. I said one thing, one time to my DD that she shouldn't let him get away with acting as he does, it just encourages him to do it more when it gets him what he wants. She didn't like that so... grandma is keeping her mouth shut.
It's her issue to deal with (even if she ISN'T dealing with it). I just hate to see him being so rude and mean to the 4 year old all the time. The 4 year old is very quiet and sensitive and he's being bulldozed by his brother and mommy isn't protecting HIM either.