1. [vulgar, informal] Irritable, angry, or bad-tempered
   "He got pissy when I asked him to clean up his mess"
    
2. [vulgar, informal] Of poor quality or unsatisfactory
   "The concert was pissy compared to their last performance"
    
3. [vulgar, informal] Smelling of or containing urine
   "The alley had a pissy odour from all the stray cats"

Encyclopedia: Pissy, Somme