My penis is the size of a peanut, have you seen it?

from Eminem – The Kids Lyrics on Rap Genius

Meaning

A peanut is a really really small nut! So his penis is really really small. Similar to common phrases such as “his brain is a size of a peanut!”

Referring to the ‘XTC’ subject which Slim is about to introduce.
XTC has a ‘tiny’ side effect, YOUR PENIS SHRIMPS!

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