Gameday spelled backwards. Used mainly by athletes, for the most part on social media, to signify that it is in fact a day on which a sporting event will take place that said person will participate in.
Cody: "Yademag!"
Neil: "What the hell did you just say?"
Cody: "It' gameday, lil niqqa!"
This is the act of taking a steamy pile of shit onto your partners bare exposed feet. Thus, leaving their toes looking like Yakima, Washington.
Jose enjoys to pay harlots in cash to give him a Yakima Steamer, while he stands in his bathtub, so he doesn’t ruin the carpet in his parents basement.