The korean spicy noodle challenge have been really popular on youtube. It doesn't taste spicy (if thats the right term) but it burns your mouth like crazy. After tasting, i kind of wanted to buy more incase I ever want to eat it again. But honestly, that package of noodle costs alot on amazon and ebay. ( i bought only 1 pack of noodle on koreadepart.com for like 1 dollar but the shipping for that is crazy too. So as a alternative, I bought this Korean capsaicin sauce to see how it taste and if it was possible to recreate the spicy noodle with this sauce. I got this sauce in the mail today and tried a dot of it and my tongue was already burning. As far as I can tell, this sauce is definitely spicier than that noodle. You can prpbly just mix a little of this sauce with your favorite ramen or other noodles and you can get similar effect of the famous spicy noodle . This bottle of hot sauce cost about $23-24 dollars for 550g (kinda a big bootle)
Update: I mixed a few small swirl of it in to my noodle... it was a bad idea. my tongue was burning like crazy and nothing could stop it. If your tongue is not sensitive, to spice, then you should try it but if not, stay far away