Kamasutra 2.9.2

2.9.2

tatra strīrūpiṇī strīyā veṣamālāpaṃ līlāṃ bhāvaṃ mṛdutvaṃ bhīrutvaṃ mugdhatām asahiṣṇutāṃ vrīḍāṃ cānukurvīta//

There are two kinds of eunuchs, those that are disguised as males, and those that are disguised as females. Eunuchs disguised as females imitate their dress, speech, gestures, tenderness, timidity, simplicity, softness and bashfulness. The acts that are done on the jaghana or middle parts of women, are done in the mouths of these eunuchs, and this is called Auparishtaka. These eunuchs derive their imaginative pleasure, and their livelihood from this kind of congress, and they lead the life of courtezans. So much concerning eunuchs disguised as females.