Buddy's first word?

The past couple of days, I swear our little guy has been screaming for me when he wants something. "Mamamamama" is a recurring sound coming out of his mouth. It's usually only used when he's angry. But our friend Catey was here, and she exclaimed, "he's calling you!" I figure that if someone who is not normally around him recognizes it, than it MUST be his first word.