First of all, I would carry several different sizes of ball point pens. Just take them apart and the front part can work like a trumpet. Try it if you don't believe me.
An old game warden told me about it. When Nebraska first opened up a Turkey hunting season, they required a hunter to carry a turkey call but didn't specify what constituted a call. When this game warden checked a hunter and asked him about his call, the hunter took apart his ball point pen and showed the game warden how he could call a turkey with his ball point pen. That satisfied the game warden.