I'm definitely voting for humor here. I know another little boy who called his mom "daddy" for about a year before saying "mommy" and would laugh hysterically afterwards. He also wasn't a huge talker at first but showed some signs of being bright (no clue if he's gifted but I know the parents are smart).
As for Collinsmom question. DH and I both had that. DH went from no words to talking in paragraphs at age 2. My mom said I went from saying words sporadically to speaking in full sentences also (but she doesn't remember the age).
As for DD she's sort of had mini-spurts. Also, while she has a large vocab (140 words at 18 months), she's still not speaking in sentences (but she does sign in them).
