Epic- Anything great, spectacular, or large/monumental in nature
Fail- An inability to complete an objective, task or job either assigned or volunteered for.
Epic Fail -A mistake of such monumental proportions that it requires its own term in order to sucessfully point out the unfathomable shortcomings of an individual or group.
Jack: Uh, dude? I may or may not have wrecked 14 ferrari's with my moped after derailing a whole train carrying nothing but kittens and puppies...
Similar to fail, but at an even larger, more pitiful scale. Sometimes so pitiful or pathetic, some will either sympathizethat person or will not say anything, due to the fail being so large that words cannot describe it.