You know how when you eat a slice of watermelon, you end up covering half your face in the sweet, watery juice?
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You look like the Joker, only fruitier.
If you hack off the corners of the rind, you leave the fruit exposed so you can eat it without face-to-fruit contact.
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And it looks purdy, like a diamond.
See? Clean cheeks, happy man.
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Now go enjoy your summer the right way!