concept of this is amusing.
yes there indeed people who have all 6 medals for this. the author of epic battle fantasy is one of them, oddly on the medals screen this game is called "medal addict"
now for advice for each medal
k: you might be able to do this one yourself, but if you want to cheat you could go get 2 or 3 nickles and put a stack of quarters on top over the k butten. be sure to release the k button when the countdowns finishes, otherwise you fail in the count of 3.
show contestant: if you can beat the other contestants or even finish 10k clicks, you got better endurance than me. to cheat you first hold down tab, and then hold down space bar as well. be sure to do only exactly 10k clicks cus if you do one click more, you have to do 1k more clicks, when your at zero, you click "claim prize". if you do 10k clicks manually, its probably better to do the extra 1k clicks cus the other contestants are probably close behind and there are no contestants in the 1k extra click run.
war hero: havent tried this yet but i suggest putting this game in pop up mode and then continue browsing newgrounds so you stay connected to the website and not be disconnected for inactivity as i think some people are are having trouble with this medal for.
human test subject: ok, i dont think this can be done alone, since a person needs 8 hours of sleep a day, you need to set up a tag team of a sort, it might still be tricky with 2 people so i suggest at least a 3 person tag team. also, if your gonna run your computer for 3 days straight, make sure your computer is dusted in,on, and around your computer, and run your air conditioner at a slightly cooler temp than what you might normally run it at. and of course have it in pop up mode to help maintain connection to newgrounds.
the pianist: if your an excellent typist, then this shouldnt be too much of a problem, if not, 2 reviews below me someone put in the words that you need for it, its not all of it though, I suspect he hit the character limit, but it should be enough for you to be able to put in the lines that disapear over the top, not too many left, got most of it down. be sure to copy it exactly, it will be under a spell checker.
john locke: i admit this one i know the least about. it would be under human test subject game. the author of epic battle fantasy has it and under its description is a bunch of numbers (4 8 15 16 23 42), my guess is you put these numbers in when its time.