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The action taken such that when having sex in a car with a sun roof, the man thrusts upward so that the woman's (Jill) head emerges through the sunroof and moans in delight. Similar to the childrens toy the Jack in a Box especially when performed with random thrusts.
I was dogging in the park last night and whacked it while watching a Jill in the Box.
by Flacido Domingo July 18, 2008
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