Stemming from a mix up of the two phrases, "Before you buy the car, you gotta take it for a test drive," and "why buy the cow when you can get the milk for free," this phrase is interchangeable with the former. You would say this if your friend wants to remain abstinent until after marriage.
Brad: CLAIRE! You can't marry him without doing the deed. What are you thinking? You gotta taste the sweet milk before you get the cow! Straight from the teet, Claire. Come on!
by EdlowetArus April 25, 2020