What does "until fork tender and the juices run clear" mean and how do I tell?

Many texts I see say that chicken is done when it is "fork tender and the juices run clear". What does that actually mean and how do I tell?

I found Is "until juices run clear" a valid test for poultry doneness? Why or why not?, but this discusses the validity of "juices running clear" as related to doneness, it doesn't really deal with how to figure out if the juices are running clear.

I am very inexperienced in the kitchen, and maybe this is a silly question, but I don't really understand this, because:

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  When I poke the chicken with a fork, it's not like enough juice comes flying out to tell what it looks like. Poking from the top doesn't lead to juices coming out due to the laws of physics, primarily the ones dealing with gravity. Poking from the side doesn't help much either. I suppose I could pierce the side and then try to squeeze some juices out, but in some cases this damages the appearance and in any case:

  
  


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  The juices are never clear when I'm actually cooking chicken, because I don't generally cook bare pieces of meat. All juice I see is inevitably clouded by whatever else the chicken is cooking in; oils, etc., often browned due to cooking.

  
  

How do I check the juices of a chicken in the oven?

Also, I also don't really understand what "fork tender" means. Pretty much any meat can be pierced with a fork at any stage in its cooking cycle. Even trying to focus on a more subtle "feel", the feel of the fork is about the same throughout the majority of the cooking except in the very beginning.

I end up just using a thermometer to check internal temperature, or pick temperatures and times that I know worked in the past for similar cuts of meat. Still, it would be nice to have another metric that I can use.