A double wolf bate typically occurs in a house occupied by three or more residents. When a person is in the shower and another housemate needs to drop a deuce. Because flushing would scald the washer....they do not flush (wolf bait has been laid). Now a second housemate needs to park a buick while the third person is still showering. In order to relieve themselves they are forced to shit on top of the other shit, hence double wolf bait.
Scott was in the shower and Andy had already used the toilet. When John came in, bunghole percilating, he asked how much longer Scott would be, but could not wait and was forced to lay double wolf bait.