Awww, heck, at that age it barely even matters what they're saying, it's that stupid sing-song voice. DS3 says all kinds of things that drive me nuts! And he is usually talking to his brother, calling him "stupid DS7". He gets upset and whines, "Mama, DS3 is calling me 'stupid DS7'!" and I say, "Ohhhh, really? And where did he learn that? From YOU calling HIM stupid!
I can (and do) punish DS3 for saying it, but as long as DS7 continues to say stuff like that to his brother, nothing is going to change. I'm hoping that will get through to his little brain one of these days!