You sadly mistaken if you thinking that I’m not on my game, boy
And things just ain’t been the same since the day that I came for it

from Eminem – Seduction Lyrics on Rap Genius

Not on your game… meaning not handling your business

Em is sayng if you think he not on his game lyrically, you’re wrong. And he changed hip-hop the day he got into the game

Wordplay: he says “game, boy” like:

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