Is it permitted for men to imitate women and vice versa?

It is not permitted for men to imitate women and vice versa. The Prophet (saw) cursed effeminate men (those men who are in the similitude (assume the manners of women) and those women who assume the manners of men, and he said, "Turn them out of your houses ." The Prophet (saw) turned out such-and-such man, and Umar turned out such-and-such woman. (Bukhari Vol. 7, Book 72, Hadith 774) حَدَّثَنَا زُهَيْرُ بْنُ حَرْبٍ، حَدَّثَنَا أَبُو عَامِرٍ، عَنْ سُلَيْمَانَ بْنِ بِلاَلٍ، عَنْ سُهَيْلٍ، عَنْ أَبِيهِ، عَنْ أَبِي هُرَيْرَةَ، قَالَ لَعَنَ رَسُولُ اللَّهِ صلى الله عليه وسلم الرَّجُلَ يَلْبَسُ لِبْسَةَ الْمَرْأَةِ وَالْمَرْأَةَ تَلْبَسُ لِبْسَةَ الرَّجُلِ ‏.‏ The Messenger of Allah (saw) cursed the man who dressed like a woman and the woman who dressed like a man. (Abu Dawud) حَدَّثَنَا مُحَمَّدُ بْنُ سُلَيْمَانَ، لُوَيْنٌ - وَبَعْضُهُ قِرَاءَةً عَلَيْهِ - عَنْ سُفْيَانَ، عَنِ ابْنِ جُرَيْجٍ، عَنِ ابْنِ أَبِي مُلَيْكَةَ، قَالَ قِيلَ لِعَائِشَةَ رضى الله عنها إِنَّ امْرَأَةً تَلْبَسُ النَّعْلَ ‏.‏ فَقَالَتْ لَعَنَ رَسُولُ اللَّهِ صلى الله عليه وسلم الرَّجُلَةَ مِنَ النِّسَاءِ ‏.‏ Ibn Abu Mulaykah told that when someone remarked to Aisha that a woman was wearing sandals, she replied: The Messenger of Allah (saw) cursed mannish women. (Abu Dawud) Al-Mannaawi (ra) said: As al-Nawawi said, this indicates that it is haram for men to imitate women and vice versa, because if it is haraam with regard to clothing then imitating them in one’s movements and tone of voice is even more abhorrent. So it is haraam for men to imitate women and vice versa with regard to clothing that is unique to one sex, and the one who does that is subject to the threat of being cursed. End quote (Fayd al-Qadeer 5/343)