Flexin' on these niggas, I'm like Popeye on his spinach
A reference to Popeye the Sailor, a 1930s cartoon character. Whenever Popeye was gettin' worked on by a villain, he’d shotgun some spinach, instantly get yolked as fuck, and ultimately turn the tables on the villain (see below for an example).
Meek loves to Flex aka show off. So much so, that he resembles Popeye.
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