so shaq is like 7’7, thereabouts and shakira’s like 4’8 or something - would it be possible for shaq to literally crush, under foot, a standing shakira? or would he have to jump?
I admire your use of the word ‘literally’.
It’s exactly the same principle as how weightlifting is literally incredibly dangerous, because the weights can crush the athletes completely flat.
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He’d have to pick up his foot 60% of his height. See if you can get your foot up 60% of your height and let me know how it goes.
Shaq’s “only” 7’1". His impressiveness is his bulk combined with his size. Yao Ming, on the other hand, is listed as being 7’6"…though the picture in my head of Yao crushing Shakira image is not nearly as fun… 
From the proposed activity, I take it you have confused Shaquille O’Neal with Jermaine. And yes, he might try it, if Ron Artest didn’t think of it first.
I’m 6’ and flat-footed can step on something 35" high (knee straight up to chest, measured from the horizontal foot to the ground). Standing on the ball of my supporting foot I can just manage 38". So that’s 48.6 - 52.7% of my total height I could “step on”.
I could get my foot higher than that of course but I wouldn’t be able to step down on that high foot and lift myself up “stair-stepping wise” on it no-hands.
So assuming Shaq has my proportions, that’s:
0.486 * 85" = 41.3" to 0.527 * 85" = 44.8" he could step down onto something. So the person he wanted to step on would have to be maximum 3’9". Shakira’s safe 
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