A phenomenon that occurs when a person over the age of consent engages in sexual intercourse with a person believed to also be over the age of consent, but later found to be a minor. The deception can occur multiple ways: the minor never discloses his/her age; the minor lies about his/her age; the perpetrator eyeballs the minor and deduces from the minor's physical features that he/she is over the age of consent; or most commonly, both persons become quite shitfaced and ignore age altogether.
A play on the word pedophile.
A pedofail that results in the arrest of the perpetrator can also be referred to as an epic pedofail.
Guy A: I finally boned Steve's sister last night.
Guy B: You know she's 15 right?
Guy B: Pedofail.
A pedophile who always fails miserably in his/her attempts to attract children.
Old guy: Hey... how's about yall visit me sometime for some popsicles... age doesn't matter to me... I just love the children...
Kids: Err... no thanks (Whisper) What a pedofail
Other kids: Twat
A PedoFAIL is paedophile who has been arrested for paedophilia and has failed.
The fucking PedoFAIL got caught in my kids bedroom.