Alphabet Pal By Leapfrog Easter Egg - Ha ha that tickles

Well, its really funny if you're 2.

1) Put Alphabet pal in letter sounds mode
2) hit A then Z
3) He says. "Ha ha that tickles"

Scared the dickens out of me the first time I heard it. Then I started poking around. There are other letter combinations that work to (C-W I think). There is no rhyme or reason as to the other Ha Ha's (symmetry, color, etc) so I assume they are the names of the programers.