In the air, and I tried hitting it with my hand, would I now have a hole there?
You have holes in your hand anyway. If you look closely enough.
I guess you are thinking of a somewhat larger micro black hole?
How about one which has a radius of 1/1000th of 1 micron? Then you would have a mass of approximately 6.73x10^14 tonnes right by your hand. If so, you will have more problems than a little hole in your hand.
By the way, hypodermic needles come in different gauges, the smallest mentioned on wikipedia is a #33, which is 203 microns in diameter, which is about 30000 times bigger than the mini blackhole we discussed above. Human cells are typically about 1 micron wide (yes, I know nerves are single cells and very big in comparison, sheesh, I said "typically").
So, you will either have a hole you would never notice or be sucked into the black hole.
Except that mini (micro) black holes are expected to evaporate pretty quickly (if Hawking is right) and the smaller they are the quicker they evaporate, so I am pretty sure you end up with black holes large enough to kill you (making the hole in your hand somewhat irrelevant) or small enough to evapourate before doing you any damage whatsoever.
PS - if your hand was held one metre from the centre of your body, you will experience an acceleration due to a black hole of the dimensions discussed above in the order of 45000 kilometers per second. This is about 4.5 million times what you experience due to gravity. That is "bad".
Separate names with a comma.