I've seen it done with a small frog.

 

How could it be done with a human being (If at all plausible)?

It would be possible, you just need a bigger magnet, which would be expensive.

It would probably be very very expensive.

You're better off putting a human with a diamagnetic material, or a superconductor and do some awesome things

As humans also contain much of diamagnetic water, it would work - BUT it's a matter of size and power.

https://en.wikipedia.org/wiki/Diamagnetism (the frog)

https://en.wikipedia.org/wiki/Magnetic_levitation#Diamagnetism

www.youtube.com/watch?v=2FvWtEdY4sE(water free surface deformed by a permanent magnet)

 

For the frog, they had 16T... JPL levitated mice later. All these are in the many-MW area, which explains why teams choose small objects or beings.