Whipping, not wiping, is when you use the slavery civic and convert population to hammers.
In the city screen, if you're in slavery, there's a button that you can use to finish an item the city is working on. It will reduce the population of the city, and for each pop point reduced it will give you 30 hammers. So a size 6 city can either take a long time to make a settler, or work for one turn on it and then whip 3 citizens away to build the settler now. (I play regular speed, YMMV)
Early game it is an excellent way to convert food to production. Later you might want to have the larger city rather than the immediate boost to production at the cost of population.
Basically it is a good tool, but like any tool you need to use it correctly.
-abs
{edit}Oh, and hey! Welcome to CivFanatics!{/edit}