What does "out of phase" sound like?

I hear lots of cautions about it but until I hear an A/B example of it I won't know it when I hear it.
Anyone have such a thing?

Thanks. I feel I have a good grasp of the theory. I just don't have any examples?
IOW Theory vs experience 

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Sometimes it's not always obvious you have a phase problem. It used to be easy to check for suspected phase problems when the phase button was on the track. It's hidden in the inspector now since X1.

 
The main problem is: "Out-of-phase" is an incorrect description of the issue.  And has been for years.
Some idiot (prolly an advertisement guy), many years ago, used the wrong word.
The correct term is "reversed polarity." Phase is about the relationship of wavs.

FYI: There is no such thing as a polarity shifter.

references:
http://www.emusician.com/techniques/0768/its-only-a-phase/143776
Phase vs. Polarity
It might be useful at this point to quickly address a common misconception. Phase and polarity do not describe exactly the same thing. As we''ve looked at already, phase is specifically about timing. When you have a phase problem, you have a problem between the timing of two things, such as the distance between two mics or latency between two DAW tracks.
 
The term out of polarity refers to two waves that may actually be in phase (i.e., they started at the same time), but whose energy is moving in opposite directions. Polarity does, indeed, relate to the shape of a wave and how it combines with others, but a problem with polarity is not related to a time offset between two similar waves the way phase is (see Figs. 4a and b). The effects of the two are often similar: When two sounds have opposite polarity, they look and behave like two sounds that are 180 degrees out of phase. But the solutions to the two problems are different, so it can be useful to differentiate them.
 
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http://www.sweetwater.com/expert-center/techtips/d--02/14/2002
First, we need to make sure we understand the distinction between polarity and phase of signals. Polarity speaks more to how the positive and negative wires are connected. Phase speaks more to a relative TIME differential between two signals.
 
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http://totalproaudio.stevebunting.com/30/basics/phase-or-polarity/
The problem is that to invert the phase of an electrical signal simply does not make sense, and what is most commonly meant is actually a polarity inversion.
 
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This is another example of why fundamental science education should be a top priorty.  NOT math and science.  SCIENCE does not require math. And Math should not be a prerequisite for science classes.
 
Math is a tool, like pencil and paper, and crescent wrenches.
 
Science is a way of observing the universe. A sister to Art.
 
 

Was looking for ages to find some audio examples and came across this site:

pls check the date before posting

Remember the old Beatles recordings with instruments very hard panned. Imagine those sounds were supposed to sound stereo. 

Out of phase is when your ex tells you that she works in the day and you work in the evening and you aren't contributing to each other

You can find a few audio examples here:  http://www.audiocheck.net/audiotests_polaritycheck.php
 

Phase concerns show up in several different ways when mic’ing a drum set.  A couple that I notice are (a) with 2 mic’s capturing the whole kit (cymbals in particular) and (b) 2 close mic’s on one drum.
 
(a) 2 mic’s capturing the whole kit
When I mic the whole kit I use an A-B spaced pair technique.  That is, 2 overheard mics facing downward to capture the cymbals about 6 feet apart from each other … 1 on each side of the kit roughly equidistant from the snare.
If you stand in a room and hit a good cymbal it will have an initial attack and then a smooth decay.  My goal is to get the mic's set to minimize phase issues and get the recorded cymbals to have this beautiful decay:
 
 
CRRrraaaassssshhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh
 
 
If you don't get the mic's set up correctly you end up with audible phase issues that sound like a rising and falling wooshing sound in the decaying cymbal wash:
 
 
CRRrraaaassssshhhhwwooosshhhhhhhhhhhhhhhwwooosshhhhhhhhhhhhhhhhhhhhhhhhhhh
 
 
(b) 2 close mic’s on one drum
Here the drum is close mic'ed from the top and bottom with the 2 mic's (at least to some degree) facing each other.  Typically what you do when mixing the 2 tracks down to 1 ... is to listen to them with the polarity matched for the 2 tracks and then flipped for the 2 tracks.  One combination will usually sound hollow and the other combination will sound fat.