Ram three "Giant Germs" to quickly meet the Summoning requirements for "Dark Armed Dragon" while dealing 1500 damage to your opponent. Note that this will cost you Life Points (unless you have "Spirit Barrier" in play) and you will be unable to attack with "DAD" until your next turn.
After this card has been destroyed by battle and two more "Giant Germs" have been Special Summoned, during your turn, Normal Summon "Junk Synchron" to Special Summon the destroyed monster. This allows you to Synchro Summon "Junk Warrior", which will gain extra ATK through the other "Giant Germs".
Because you can Special Summon any number of "Giant Germs" with this card's effect, only Summon the amount that you need. If you plan on using one in a Synchro Summon or Tribute Summon, Summon both so that you will thin your Deck and have a Tribute. If you intend to allow the opponent to kill it in battle and do not care to thin the Deck by one card immediately, the second "Giant Germ" can Special Summon the third.
Usually, your best bet is to Special Summon both at once, If you draw the third before the second is in your hand, you cannot Special Summon it and it is almost a complete Dead Draw. Only Summoning one, however, will prevent both from being destroyed by "Dark Hole" and the like.