SB 11.17.33

strīṇāṁ nirīkṣaṇa-sparśa-
 saṁlāpa-kṣvelanādikam
prāṇino mithunī-bhūtān
 agṛhastho ’gratas tyajet
Synonyms: 
strīṇām — in relation to women; nirīkṣaṇa — glancing; sparśa — touching; saṁlāpa — conversing; kṣvelana — joking or sporting; ādikam — and so on; prāṇinaḥ — living entities; mithunī-bhūtān — engaged in sex; agṛha-sthaḥ — a sannyāsī, vānaprastha or brahmacārī; agrataḥ — first of all; tyajet — should give up.
Translation: 
Those who are not married — sannyāsīs, vānaprasthas and brahmacārīs — should never associate with women by glancing, touching, conversing, joking or sporting. Neither should they ever associate with any living entity engaged in sexual activities.
Purport: 

Prāṇinaḥ indicates all living entities, whether birds, bees or human beings. Among most species of life, sexual intercourse is preceded by diverse mating rituals. In human society, all types of entertainment (books, music, films) and all places of amusement (restaurants, shopping centers, resorts) are designed to stimulate the sexual urge and create an aura of “romance.” One who is not married — a sannyāsī, brahmacārī or vānaprastha — should rigidly avoid anything related to sex and of course should never see any living entity, whether bird, insect or human, engaging in the various phases of sexual intercourse. When a man jokes with a woman, an intimate, sexually charged atmosphere is immediately created, and this should also be avoided for those aspiring to practice celibacy. Even a householder who becomes attached to such activities will also fall down into the darkness of ignorance.