Sounds cheesy, I use my wedding ring... put it up to my lips sideways, and about 1/3 way in then blow. I had it work quite a few times last season during the rut, once actually had 2 8 pointers come in at once, one from my left and one from the right, couldn't get a shot at either...

DISCLAIMER>>> This isdefinately the most expensive call I own, and I don't mean $$$ cost.... and you always have it with you. (at least you better.)