Kevin is usually the one who is good at coming up with funny lyrics for songs.  One of Tyler's toys plays the music for "Twinkle Twinkle Little Star" and Kevin sang "Tinkle Tinkle In the Car".  For some reason, an entire verse for this variation popped into my head:
<p style="text-align: center;"><em>Tinkle, tinkle in the car
Boy, I'm glad I brought a jar</em>

<p style="text-align: center;"><em>It's no fun when your seat's all wet
Had to make do 'cause we're not there yet</em>

<p style="text-align: center;"><em>Tinkle tinkle in the car
Why'd we have to drive so far</em>
<p style="text-align: left;">Don't ask me where it came from, it just popped fully formed into my head.  I'm not quite sure what that says about me...</p>