take the piss

verb3

1. •
   (slang, vulgar) To tease, ridicule or mock (someone).

   • You know, cos he was like taking the piss out of them and they took the piss out of him. — 1987
2. •
   (slang, vulgar) To subject those present to teasing, ridicule or mockery, or to show contempt.

   • He's either taking it easy or taking the piss by arriving at the eleventh hour. — 2008
3. •
   (slang, vulgar) To be outrageously unreasonable.

   • I've got three exams on the same day! That's taking the piss!