Not a good idea.
The little bird could die.
How to sneak a budgie/small bird into middle school? I have a case that looks like a lunchbox and i can put food and water
I can't see why you would? What's more important?
1. For your friends to possibly see the bird.
2. For the bird to live.
Um. Just don't. All that shaking and jostling about will cause stress and trauma for the bird.
Refreshme is right, the bird might not die, but it’ll be very stressed out, stuffed into a lunchbox or backpack all day. Hell, not even a locker is enough room for a budgie. Is there an animal and agriculture classroom? Maybe you could ask them if you can set up a bigger cage in there?