The Legend of Zelda for the original Nintendo gaming system is the best video game ever. This is not an opinion, but a statement of fact.
Ok, now that we've gotten that out of the way, I can explain exactly what this has to do with the Grub.
Early on, when the Grub only wanted mommy 24/7 (and, let's be honest - this was mostly just for feeding purposes), JK realized he needed to get creative in his approach to interacting with Monica. So he downloaded an Ocarina player app to his phone and taught himself to play the theme song from The Legend of Zelda.
JK started playing this song for her when she was just a little squirmy grub who couldn't really get around on her own.
Now, to our surprise and delight, upon hearing the first few notes of the tune, our little grub comes scampering over to perch on Daddy's knee and listen to the song.
An ocarina is an ancient flute-like wind instrument. Additional information about the ocarina can be found here.
In the Nintendo 64 game, The Lengend of Zelda: Ocarina of Time, an Ocarina was given to Link for questing purposes. Throughout the game, the player learns twelve melodies that allow Link to solve puzzles and teleport to various locations.
While our Ocarina doesn't result in cool things like teleportation abilities, it certainly seems to entertain this little grub. She says, "Daddy, if you work on your ocarina skills, I'll work on learning to play a string instrument, and we can start a band!"
At this point in time, she could probably start her own string band, as she has been working on systematically removing the string ties from every pair of pajama pants that I own (as seen to your left). But, hey, I'll consider it a small price to pay when our little musical genius makes it big and is able to support JK and I in our old age. Play on, Grubster!