How do I tell my nephew that his posts on facebook are not appropriate without offending him?

My nephew is obsessed with sex and the male anatomy ( he is 30 yrs old) He carved a pumpkin and carved out a penis with ball.. and then carved "trick or meat" and posted it on facebook. .. my investment in this is that I helped raise him from a baby... so he is like my son. Do I just ignore it or say something? If you all think I should say somthing.. What do I say?