Why? Because I've put stranger things on my penis before. Like your mom, OHHHHHHHHHHHHHHH.
Using beef jerky as a condom to prevent pregnancy and the spread of sexually transmitted diseases probably is not effective at all. In fact it will probably introduce newer diseases.
It will, however, be hilarious. Just think of your girlfriend or wife's face when you come into the room wearing your birthday suit and a condom made of a wad of hickory smoked beef jerky. It will, no doubt, increase oral pleasure especially if your significant other likes salty snacks.
Do you have any ideas of using beef jerky in the bedroom? Also, tell your mom I said "Hi" OHHHHHHHHHHHH