Peek-a-boo, Beebo

The special vocabulary that adults use in talking to babies has the potential to be very family-specific. After all, you're talking to a baby, who can't talk back (yet) and who's getting little other language input outside the family, so why not just make things up? We've got a number of 'inside jokes' that we use with Grover. For example, despite her lady-like appearances, Grover is a very farty baby. We started out saying poot poot when we heard the reports from down south. Then we'd say Are you pootin'? And this has turned into Is that you, Vladimir? So now, Vladimir = farty baby. And then there's the fact that we say knickerschnitz whenever Grover sneezes, which goes back to my brothers convincing (well, almost) my sister-in-law that this is what the English say instead of Gesundheit (which is, in fact, more popular in the US than in the UK).

But at the same time, babytalk is remarkably widespread within a culture--though the ocean often gets in the way of a generic, international babytalk. When talking to babies, we call cats kitties and wounds (orig. AmE) boo-boos. There's (BrE) bicky for (BrE) biscuit and (chiefly AmE) choo-choo for a train. And so on and so forth.

So, when I hear Better Half or his family using new-to-me babytalk, I'm never sure if it's something that's part of their 'family-lect' or more generally part of BrE. Since there may be a natural tendency to view one's in-laws as strange ('they're a family, but they don't do thing the way my family does!'), I tend to assume that their babytalk is 'theirs' until I hear someone else use it. Such was the case with (BrE) windy-pops, which came up in the comments back here. Now, I've found another case.

When I play the game Peek-a-boo with a baby, I hide my face, then show it suddenly and say Peek-a-boo! in a sing-song voice. Sometimes I vary it and say "Here I am!" or "There you are!", which follow the same three-syllable tune. And that's the only way that I've known the game.

But when BH's mother plays it, she says Beebo! I make a mental note to say peek-a-boo twice as much later, to reassert my influence (Jealous? Moi?), and put it down to her own creativity. Then I heard BH's sister say it, and I figured that she learned it from her mother. But then...we had a picnic in hono(u)r of Grover's half-birthday with other parents and babies, and I heard another mother say Peebo! So, yet another occasion on which I learn with disappointment (but, alas, not surprise) that I'm the strange one, not my in-laws.

The Wikipedia entry on peek(-)a(-)boo mentions nothing about alternative exclamations, but the OED mentions peep-bo and bo-peep. I've also found this line from a London blogger, indicating that the variation in interjections is well known in these parts:
We've been playing beebo, peepo, peekaboo, whatever you want to call it for months.
So, am I right in thinking that most Americans stick to peek-a-boo? Are there other alternatives?

And is Better Half the only person who calls hands pandies or is that general BrE babytalk? (AmE snowclone): Enquiring babies want to know! I know this derives from the nursery rhyme Handy Pandy, but I'm wondering about pandy on its own.