Why do people hold their breath when crossing bridges?

Question

I just went on a school camp and many of my friends held their breath while going over bridges in the bus. Why?

Answer 1

Superstition has a funny way of affecting a whole bunch of people in a myriad of ways.

Answer 2

some get nervous.....

Answer 3

Just superstitions. Like holding your breath while going past a cemetery so "spirits don't get in your soul" or whatever it is.  

Answer 4

It's just a silly thing that kids do, like lifting your feet when crossing railroad tracks, or ducking when going under bridges.

Just something to do on the trip - there is no valid reason

Answer 5

there a bunch of pussys