A peak bike is someone who is always 'peaking'/paranoid about something or other, or is just peaky and bait to be around.
Jackson: "Hey guys, did you hear that? I think we're being followed"
Everyone: "God Jackson you're such a peak bike"
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Justin: "Hey you know what lads I'm gonna roll a joint"
Everyone: "You're such a peak bike Justin, we're sitting right outside the police station"
Everyone: "God Jackson you're such a peak bike"
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Justin: "Hey you know what lads I'm gonna roll a joint"
Everyone: "You're such a peak bike Justin, we're sitting right outside the police station"
by Yaooo March 10, 2013