What is the meaning of these slang terms used in ATC?
Follow the black holes

I have no idea about this one. I looked at the airport diagrams and arrival/departure procedures for MIA, MCO and ORL and I couldn't see anything that seems like it could be confused with the words "black hole". So, I have two guesses:


It's the code name for a set of local taxi instructions
As you suggested, it's the controller's slang for "the twin-engine aircraft in front of you", i.e. the black holes are the exhausts


I think the second possibility is very unlikely, though. A controller at a major international airport - which implies many pilots with English as a second language - is unlikely to use non-standard phrasing for a critical instruction like which aircraft to follow.

Taxi not too deep

This one is a lot clearer from the updated comment you gave: "CLEARED PUSHBACK, NOT TOO DEEP, THERE IS A TRAFFIC PASSING BEHIND YOU". That's exactly what it sounds like: the aircraft was cleared to push back from the gate, but the ground controller was warning the pilot not to push back too far ("too deep") because of another aircraft passing behind.

How is your ride?

This one is ATC asking a pilot for a PIREP. That could be because another aircraft nearby is in turbulence and trying to find a smoother altitude, so the controller asks other aircraft about the ride at their flight levels. Or, since you heard this in the US, it could be for this reason, from the AIM section 7-1-20:


  FAA air traffic facilities are required to solicit PIREPs when the
  following conditions are reported or forecast: ceilings at or below
  5,000 feet; visibility at or below 5 miles (surface or aloft);
  thunderstorms and related phenomena; icing of light degree or greater;
  turbulence of moderate degree or greater; wind shear and reported or
  forecast volcanic ash clouds.


Are there other examples of slang?

I'm sure there are, although slang in general is discouraged because of the potential for misunderstandings. The FAA has a pilot/controller glossary to make sure that everyone is using the same words and phrases as far as possible (ICAO provides one too), but that doesn't mean that people always stick to it 100% of the time. Ex-military pilots - and controllers - in particular sometimes use some military terminology (e.g. bingo fuel) out of habit (presumably) even though they really shouldn't in a civilian setting.