milkshake Share definition Flag milkshake is when a girl licks a guys butthole, therefore "Kelis" is refering to shes good at licking other guy's asses. I gave him a milkshake last night and it made him crazy milkshake by Mackenzie February 20, 2004 0 0 Get merch Get the milkshake mug. Buy Now — $32.95 See more merch