One I actually used several years ago (to a very few "friends").

On the outside cover, draw a part of a circle - the "northwest" quadrant or a little less.

Sort of "inside" where the full circle would be, you draw three or four "triangles" with one side missing.

On the ends of the "legs" of the triangles, where the other side would have been, you draw "arrowheads."
Sprinkle a few musical notes (dots) around the whole thing.

Inside, if you're brave enough, it reads:

"Arc the arrowed angles sing."

groan and drum rip.

And apologies

John