If you rubbed a balloon with a towel, where would the electrons go: the balloon or the towel? Why?
I'm guessing the electrons would go to the object with a larger mass, but it's just a guess. :)
This article on triboelectricity gives a triboelectric series, listing materials according to whether they will expel electrons or acquire them , when rubbed or in contact.
Towel is not in there :) but cotton is, with 0 but it is more positive than rubber. So the answer is that the electrons will move to the balloon, if you manage to get cotton to give up its electrons :) . Did you do the experiment? A woolen towel would be much better. Maybe it was your hand that gave up the electrons after all.
This is what wikipedia has to say on the causes:
Hence the need of a table.