This word appear in the comment of a video of Bach in YouTube:
A: Which minute is the drop?
B: When he and Mozart have the rap battle
Clearly this is a joke, but I don't understand the meaning of the drop. I have looked up in Oxford Dictionary, but all the meaning only point to the drop of liquid, or the action of dropping. I have also looked at the Urban Dictionary, but the meaning of the noun of drop is an expensive car, which doesn't make sense to me.