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(blends granny and ninja) n. When you think you're running it up at the park, and look behind you to see these old ladies matching your speed.
Person 1: I was running at the park the other day when these two old ladies came out of nowhere behind me.
Person 2: Ya, those grinjas can be sneaky.
Person 2: Ya, those grinjas can be sneaky.
by Hoosker-doos August 28, 2014