Its not a Hallucination, but there have been several instances where i have been woken up by music that i played in a concert the day before, or one extreme example:
I was in that half asleep, half awake mode and i was literally at Marching band practice in my head, i had come home from a late practice and was trying to get some sleep before the competition and the only thing i could do was freakin dream about practice.
It pissed me off.