i agree with the above comments,if your friend is going to have sex please make her aware she needs to use a condom,How did the implant fall out? was it by accident or did the skin reject the implant?
when you say implant do you mean an iud? like mirena or paragaurd? she should call her ob asap. and NOT have unprotected sex until she see's him/her.
How the hell did it fall out!? 0_0
Now im assuming you mean Implanon that goes in your arm? cause thats just...odd
But yes, straight to the doctors!
If you are referring to any sort of contraceptive, your friend should not have unprotected sex, and should let her doctor know right away.