Interesting - i think that might depend on the kind of whiskey, as well as any added colouring in there. In europe its legal to color whiskey with caramel (same as used in cola), which could result in the brownish fluorescense observed.
Some fluids have fluorescent dyes to detect leakages - coolant could be one of them, but its also frequently used as a tracer to find air conditioner leaks in cars. Those substances arent good for experiments though, since they mostly boil at room temperature. You could dissolve the dye in another nonpolar solvent to keep it at room temp without the solution evaporating that quickly.