When will my two year olds testicles drop?

Confusing question. The testis normally descend into the scrotum around the 28th week of pregnancy. There persence may be dificult to verify due to peroneal fat, or the presence of fluid in the sac like structure that surrounds them. I don't know what u mean by drop. If your 2yo's testis are not in the scrotum, u should see his dr.Undescended testis have reduced fertility & most like to bring them down by 1yo.
Time to get fixed. While frequently testicles may not have descended at birth they should descend within the first few months of life. Not only can undescended testicles loose there furtility and be a cosmetic issue for men they can also be a source of cancer if untreated.