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mash something up
to crush something into a paste or pieces. Mash the potatoes up and put them in a bowl. Mash up the potatoes and serve them to our guests.
1. To combine some recordings to produce a composite recording: The DJ mashed popular songs up. The DJ mashed up two songs by The Beatles. The DJ mashed the popular song up with an old blues song.
2. To mash something completely: The cook mashed up the potatoes. I threw the turnips into a bowl and mashed them up.