>>529294908
>slang
In context, it's supposed to be culturally trendy/"cool" that Sonic peppers in some English, so that's pretty much all you can do. Problem is that you have to be careful not to go overboard or you risk affecting the characterization too much.
Alternate idea: you can emphasize that Sonic's a world traveler and would pick up words from the places he's traveled to. This doesn't usually work unless the character's supposed to be a foreigner, though, and they oddly enough do this to Robotnik in the live-action movies.