Kamasutra 2.2.16

2.2.16

caraṇena caraṇam ākramya dvitīyenorudeśam ākramantī veṣṭayantī vā tat pṛṣṭhasaktaikabāhur dvitīyenāṃsam avanamayantī īṣan mandasītkṛtakūjitā cumbanārtham evādhiroḍhum icched iti vṛkṣādhirūḍhakam//

(2) When a woman, having placed one of her feet on the foot of her lover, and the other on one of his thighs, passes one of her arms round his back, and the other on his shoulders, makes slightly the sounds of singing and cooing, and wishes, as it were, to climb up him in order to have a kiss, it is called an embrace like the "climbing of a tree."