The Messenger of Allah ﷺ prohibited drinking by inverting the heads of skin vessels.  

أَنَّ رَسُولَ اللَّهِ ﷺ نَهَى عَنِ اخْتِنَاثِ الأَسْقِيَةِ  

Invert the head of the vessel and he drank from its mouth.  

أَنَّ رَسُولَ اللَّهِ ﷺ دَعَا بِإِدَاوَةٍ يَوْمَ أُحُدٍ فَقَالَ اخْنُثْ فَمَ الإِدَاوَةِ ثُمَّ شَرِبَ مِنْ فِيهَا