Kamasutra 7.2.25

7.2.25

evaṃ vṛkṣajānāṃ jantūnaṃ śūkair *upaliptaṃ liṅgaṃ daśarātraṃ tailena mṛditaṃ punaḥ *punar upaliptaṃ punaḥ pramṛditam iti jātaśophaṃ khaṭvāyām adhomukhas tad antare lambayet/

When a man wishes to enlarge his lingam, he should rub it with the bristles of certain insects that live in trees, and then, after rubbing it for ten nights with oils, he should again rub it with the bristles as before. By continuing to do this a swelling will be gradually produced in the lingam, and he should then lie on a cot, and cause his lingam to hang down through a hole in the cot. After this he should take away all the pain from the swelling by using cool concoctions. The swelling, which is called Suka, and is often brought about among the people of the Dravida country, lasts for life.