Okelpenning
A variety of Denier, the precise etymology being unknown. In an ordinance of 1314, Johann V, Margrave of Brandenburg is authorized to coin certain Deniers "qui vulgariter Okelpenninge vocantur." In Pommeranian archives of the year 1325 they are called Denarii Augmentabiles, and in Brandenburg at a somewhat later period they are referred to as Kelpenninge. See Kehlpfenning.
Source: Frey's Dictionary (American Journal of Numismatics, Vol. 50, 1916)