Garudapurana 2.4.145

2.4.145

vṛntākaṃ vṛṣaṇadvandve liṅge syādgṛñjanaṃ śubham /
ghṛtaṃ nābhyāṃ pradeyaṃ syātkau pīne ca trapusmṛtam //

An eggplant on the two testicles, and a carrot should be auspicious for the penis;
Ghee should be given at the navel, and tin is prescribed for the loincloth;