What you'll need:
1 bicycle horn
Instant grab fast dry glue
How to make it:
Pipe a line of instant grab glue down the length of the horn.
Gently press sequins into the glue. Repeat steps 1 and 2 until you've gone all the way around the horn.
Glue some sequins around the ring near the horn's bulb.
Other decorative items you could use are glitter or small beads.
Instant grab glue is available from your local craft supply store.