I can tell you're waving your hands back and forth, and given that we can't see exactly what your arms are doing, the most likely explanation I can think of is when waving your hands back and forth, you're shaking the table (directly or indirectly) which is causing the water to move a bit.

I can do this too with my computer monitors. If I wave my arms around like you seem to be doing, it causes my chair to move back and forth with me, which shakes the floor, shaking the table, and ultimately shaking my computer monitors.

Alternatively, you could also easily be pushing air around by waving your hand like that, and if the air passes over the cup, the air in the cup will resonate, also causing the water to move. This is most likely what's happening, if you really can make the water "dance with music" - sound waves are resonating in your cup and making the water vibrate.

You're high. Go to bed. Sleep it off.