Fwiw, in most of the Bronx, people use private car services. Only the rough and tumbliest riders actually hail the gypsy cabs --that go where the yellow ones won't. In general, I don't think you'd a very different reaction. I don't think that most Bronxites who ride bikes would ever think of high-fiving someone hailing a cab. It's more a matter of manners. It's true that, if someone took it as a diss, there could be problems.
I just tried to imagine a "candid camera" or "punk'd" or even "Scare Tactics" in the South Bronx. A guy would jump out, ask "Are you scared?" and get a "Hell no, mf, take this! Now, are You scared?"
"A man is rich when he has time and freewill. How he chooses to invest both will determine the return on his investment."