And I rap myself right to this bubble
Oh I guess it's bubble wrap

from 50 Cent (Ft. Adam Levine & Eminem) – My Life Lyrics on Rap Genius

Meaning

“uh oh”, basically says, “here comes another pun” but he says it on the offensive, as if he were deliberately attacking someone for putting his puns/metaphors down (everyone).

Seen from his Recovery album cover and other lines, Em feels like he has been in his own bubble since he got back to rap. No one truly understands what hes trying to say in his music. He masks everything in metaphors so that only some people understand what hes talking about. But by rapping more and more, he pushes himself further into the bubble. So he uses a little wordplay with bubble wrap here.

The line references similar lines in Say Goodbye to Hollywood and Take from Me

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