A piggy back, huh?
Well, your animation is alright, though there was not much to animate.
What gets me is the joke. It was pretty bad. Like, if this came to my mind I definitely wouldn't put it into a Flash, yikes.
I'd say instead of pushing to think of something to make a Flash about, write something down that comes to you out of the blue, then make THAT into a Flash. It'll be better.
Good luck.