Nuke's pills come in three different colors - red, white and blue - each meant to produce a bodily effect to change his mood. The red pills increase his adrenaline, the white bring him down and the blue relax him. Nuke tends to abuse the red pills which has lent to him regularly exclaiming "Give me a red!" as if it were a catchphrase.
It was later revealed that the pills themselves are nothing but placebos, and they have no real effect on Nuke's mental state at all.