Can someone plese tell me what this phrase means. I am a teacher at a high school in Oklahoma and an student keeps writing this on his desk. I cannot find anyone to translate this for me(without havig to pay for it). I apologize if it is in any way offensive.
 
Американцы долбоёбы

I know the first word is American, but i do knot know the secone one.

I appologize...Thank you anyway.