I'm not sure how "lose" got replaced with "fail", but hackers have been using "win" in the same sense since long before 4chan came along. Also, using a designated but unusual superlative -- "epic fail" -- is a common hacker speech pattern, as with "die horribly" or "grok in fullness".
I sometimes wonder how "normal" people perceive this mass of variously geeky people on the net who practically speak a different language by now. I sometimes wonder how my parents would react if I sent them an email declaring that "I pwn3d some n00bs".
Probably the same way that their reacted when they told them that mellowing out was groovy. Or the way _their_ parents reacted when they told them that the hep cats were jumpin'. Or the way _their_ parents reacted when told that some bird was the bee's knees.
Shrugging and invisibly rolling one's eyes seems like appropriate.