>>127748524
It's a cassette tape you make filled with songs you like for a girl you've got a crush on. You give it to the girl to listen to and then ask which of the songs she likes too. It's a great icebreaker / conversation starter and gets the two of you talking about music and hopefully becoming friends. Then maybe she makes you a mixtape of her own. There are other variations of the mixtape - some guys fill it entirely with songs that are trying to tell the girl "I'M IN LOVE WITH YOU" in the lyrics whereas others prefer to do their most personal favorite songs ever to see if the girl shares the same emotional taste on a deep subconscious level.
I should also mention in the rap community they use the word mixtape too, but they use it wrong and it means something totally different. Their "mixtape" is not a tape at all, it usually refers to a rapper's first album or even a demo. So why do they call it a mixtape? Because rappers are fucking retarded.