A Bucks County Criminal Jury heard a shaggy dog story this week and believed it.At a trial in Doylestown before Judge Lawrence A.Monroe, Bristol Township police testified that David F. Gross, 21, of 10 Plumridge Road, Levittown, took a Shetland Sheep Dog without theconsent of the owner.Gross was charged with larceny. The animal was valued at $800.But Gross testified that he took the dog last May 5 from the yard of Harry Hamp, 312 Lakeland Ave., as “a• joke.”He said he and some com-panions had been drinking when they entered the yard of Hamp. The group was boisterous and no stealth was. involved, Gross said.%Gross s*aid he took the dog ; to a couple of bars. At one - tavern, the animal was treat-; ed to a bowl of milk, the de-• fendant said.Gross was acquitted.