Ekaiser

Knowingly keeping a third parties item/belongings once its rightful owner is found. More or less indirectly stealing something. To Ekaiser someone is to not relinquish previously unclaimed goods once the rightful owner has come forward.

Guy 1: Hey I know I gave you that Armani blazer that was left at my house after the party, but I found out it was Jimmy's brothers coat after all and he wants it back

Guy 2: Yeah well you did give it to me, tough luck pal you're not getting it back

Guy 1: You're a fucking grease-ball, way to Ekaiser his brother man