Be Prepared Skit

4 scouts
airhorn or siren or even trashcan lids to make a startling loud noise.

have one scout in the back of the audience by the last part of the skit.

This skit fills in between other skits. You need to arrange it with the program leader so he does not announce it as a skit and understands how it works.

First scout seriously walks to center stage, makes the scout sign and waits for silence. When it is fairly quiet, loudly proclaims "Be Prepared!" and then walks offstage.
Another skit or announcement or song.

Second scout walks to center stage, raises scout sign and waits for silence. When quiet, proclaims "Be Prepared!" and walks off.
Another skit.

Third scout does the same thing.
Another skit.

All three scouts walk center stage and hold up the sign. The fourth scout needs to be in back of audience ready to make noise. When the scouts lower their signs, the one in back blows the horn hopefully startling the audience.
All three scouts say, "We told you to BE PREPARED!"