pkpk was crying last night and now her eyes are swelled up.  Tears are strange; you cry when you're happy and when you're sad.  This discussion of tears reveals a terrifying plot!
Happy and sad into one feeling?
¿Tristeza y felicidad en un mismo sentimiento?
¿Unir la tristeza y la felicidad en un mismo sentimiento?
Fazer da alegria e da tristeza 
um mesmo sentimento?