I recently had an IUD inserted and I was wondering what the likelihood of getting pregnant would be if a man ejaculated inside me with out any other form of protection and if that should happen should I use a form of back up protection (like morning after pill or spirmacide)?

While pregnancy is possible with an IUD, it is not common. Most women who have an IUD do not use additional forms of contraception.

Certainly it can be helpful to use an additional form of birth control. A condom for the male would be wise as it would also help to protect you from more than just pregnancy. What sort of IUD do you have in place? If a Mirena, it may not be wise to also use the morning after pills due to the higher concentration of hormones... some of which you would already be getting with the IUD.