Get on your Harley Davidson menstrual cycle
And ride it like a motorbike

from Eminem (Ft. X Ambassadors) – Wicked Ways Lyrics on Rap Genius

Meaning

A menstrual cycle is the scientific name for a girls period. This is a play off motorcycle.
A Harley Davidson is a very nice motorbike/motorcycle that a dyke might enjoy riding (reference to the previous line)

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