take an hour to wear off

  • Apparently the two doctors have invented an invisibility potion. After one hour, they will no longer be invisible. So, since they have one hour to do basically whatever they want, the one doctor is asking the other what he wants to do.
    To me, is that the effect of the invisible solution works for only one hour, and after that they will be seen again.

    The point, well what can you do for being invisible for an hour? I imagine a lot of pranks. :)