http://www.sexualrecords.com/WSRphysiology.html

The ideal testicle, which we are clearly not talking about here, should measure about 4 cm long and 2 cm broad. Victims of elephantiasis, a disease caused by the obstruction of lymph vessels due to parasitic filarial worms, may find their gonads swelling to the size of a Watermelon and beyond. The largest on record is an African whose scrotum weighed 154 lbs. and measured almost 2 ft. in diameter.

http://curezone.com/ig/viewphoto.asp?i=002.jpg&f=parasites/different_photos