To 'pat' someone is to throw one's excrement, especially faeces, at them.
Ladies may also choose to throw used menstrual regalia instead of faecal matter.
One may commit the ultimate pat by furnishing one's bowel with the necessary materials before positioning oneself directly above the head of a friend, relative or perhaps passing person, thence one proceeds to pat them right on the head.
Katy was constantly banging on about her wide-set vagina, which finally pushed Alex to the point of patting her with sloppy twos.
Alex had been a dick to Katy so she pat him. She pat him good.
Katy's menses had stained Alex's favourite shirt after the pat attack, therefore he fucking killed her dead. Bitch.