Pelle says he pranked Van Gaal when he was on the verge of signing for the Dutchman's AZ Alkmaar side.
Pelle revealed: "We were talking about the shirt number and I like number 9 because it's the classic one of the striker. We went through the possible numbers, like 19, 90 or 99, but I didn't want those high numbers.
"Eventually I jokingly said in that case I'm not signing for the club. He was so severe and was absolutely furious, jumped up and asked my agent how I could possibly do such a thing.
"I told him sorry, I was joking! He's a great coach, though."
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